Advanced parallel processor including advanced support hardware

ABSTRACT

A parallel array processor for massively parallel applications is formed with low power CMOS with DRAM processing while incorporating processing elements on a single chip. Eight processors on a single chip have their own associated processing element, significant memory, and I/O and are interconnected with a hypercube based, but modified, topology. These nodes are then interconnected, either by a hypercube, modified hypercube, or ring, or ring within ring network topology. Conventional microprocessor MMPs consume pins and time going to memory. The new architecture merges processor and memory with multiple PMEs (eight 16 bit processors with 32K and I/O) in DRAM and has no memory access delays and uses all the pins for networking. The chip can be a single node of a fine-grained parallel processor. Each chip will have eight 16 bit processors, each processor providing 5 MIPs performance. I/O has three internal ports and one external port shared by the plural processors on the chip. Significant software flexibility is provided to enable quick implementation of existing programs written in common languages. It is a developable and expandable technology without need to develop new pinouts, new software, or new utilities as chip density increases and new hardware is provided for a chip function. The scalable chip PME has internal and external connections for broadcast and asynchronous SIMD. MIMD and SIMIMD (SIMD/MIMD) with dynamic switching of modes. The chip can be used in systems which employ 32, 64 or 128,000 processors, and can be used for lower, intermediate and higher ranges. Local and global memory functions can all be provided by the chips themselves, and the system can connect to and support other global memories and DASD. The chip can be used as a microprocessor accelerator, in personal computer applications, as a vision or avionics computer system, or as workstation or supercomputer. There is program compatibility for the fully scalable system.

This is a continuation of application Ser. No. 07/887,612, filed on May22, 1992, now abandoned.

This is a continuation of application Ser. No. 08/380,230, filed on Jan.30, 1995 now abandoned.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority and is a continuation-in-part ofthe following related co-pending patent applications:

U.S. patent application Ser. No. 08/301,278 filed Sep. 6, 1994, which isa continuation of application Ser. No. 611,594 filed Nov. 13, 1990, ofJ. Dieffenderfer et al., entitled "Parallel Associative ProcessorSystem"; now abandoned, and

U.S. patent application Ser. No. 08/324,295 filed Oct. 17, 1994 is nowU.S. Pat. No. 5,475,856 of P. Kogge entitled "Dynamic Multi-ModeParallel Processor Array" which issued Dec. 12, 1995.

In addition, this application is related to the following applicationsfiled concurrently herewith:

U.S. patent application Ser. No. 08/558,763 filed Nov. 15, 1995, whichis a continuation of application Ser. No. 08/356,039 filed Dec. 14,1994, which was a continuation of application Ser. No. 08/274,127 filedJul. 12, 1994, which was a continuation of application Ser. No.07/887,718 filed May 22, 1992, of P. Wilkinson et al., entitled "SIMIMDArray Processing System";

U.S. patent application Ser. No. 08/460,515 filed Jun. 1, 1995, which isa continuation of application Ser. No. 07/887,514 filed May 22, 1992, ofP. Wilkinson et al., entitled "Floating Point For A SIMD Array Machine";

U.S. patent application Ser. No. 08/431,617 filed May 1, 1995, which isa continuation of application Ser. No. 07/887,455 filed May 22, 1992, ofP. Wilkinson et al., entitled "Array Processor Having Grouping of SIMIDPickets";

U.S. patent application Ser. No. 08/458,859 filed Jun. 1, 1995, which isa continuation of application Ser. No. 07/887,456 filed May 22, 1992, ofP. Wilkinson et al., entitled "Slide Network For An Array Processor";

U.S. patent application Ser. No. 08/430,931 filed Jun. 7, 1995, which isa continuation of application Ser. No. 07/887,256 filed May 22, 1992, ofP. Wilkinson et al., entitled "Picket Autonomy On A SIMD Machine";

U.S. patent application Ser. No. 08/292,943 filed Aug. 18, 1994, whichis a continuation of application Ser. No. 07/887,459 filed May 22, 1992,of P. Wilkinson et al., entitled "Controller For A SIMD/MIMD ProcessorArray"; and

U.S. patent application Ser. No. 08/430,708 filed Apr. 27, 1995, whichis a continuation of application Ser. No. 07/887,997 filed May 22, 1992,of P. Wilkinson et al., entitled "Array Processor Dotted CommunicationNetwork Based On H-DOTS".

Futher this application is related to:

U.S. patent application Ser. No. 07/887,630 filed May 22, 1992, of T.Barker, et al., entitled "Advanced Parallel Array Processor";

U.S. patent application Ser. No. 08/459,374 filed Jun. 2, 1995, which isa continuation of application Ser. No. 07/888,000 filed May 22, 1992, ofT. Barker, entitled "SIMD/MIMD Processing Memory Element";

U.S. patent application Ser. No. 08/459,380 filed Jun. 2, 1995, which isa continuation of application Ser. No. 07/993,255 filed Dec. 18, 1992,of T. Barker, entitled "PME Store and Forward/Circuit Switched Mode";

U.S. patent application Ser. No. 08/468,500 filed Jun. 6, 1995, which isa continuation of application Ser. No. 07/887,508 filed May 22, 1992, ofT. Barker, entitled "Fully Distributed Processing Memory Element";

U.S. patent application Ser. No. 08/519,859 filed Aug. 25, 1995, whichis a continuation of application Ser. No. 08/380,230 filed Jan. 30,1995, which was a continuation of application Ser. No. 07/877,612 filedMay 22, 1992, of M. Dapp, et al., entitled "Advanced Parallel ProcessorIncluding Advanced Support Hardware";

U.S. patent application Ser. No. 08/412,025 filed Mar. 28, 1995 which isa continuation of application Ser. No. 07/587,512 filed May 22, 1992, ofM. Dapp, et al., entitled "Advanced Parallel Array Processor ComputerPackage";

U.S. patent application Ser. No. 08/282,101 filed Jul. 28, 1994, whichis a continuation of application Ser. No. 07/888,684 filed May 22, 1992,of T. Barker, et al., entitled "N-Dimensional Modified Hypercube"; and

U.S. patent application Ser. No. 08/430,114 filed Apr. 27, 1995, whichis a continuation of application Ser. No. 887,258 filed May 22, 1992, ofM. Dapp, et al., entitled "APAP I/O Programmable Router".

U.S. patent application Ser. No. 08/400,687 filed Mar. 8, 1995, which isa continuation of U.S. patent application Ser. No. 07/887,259 filed May22, 1992, of T. Barker et al. entitled "APAP I/O Zipper Connection".

U.S. patent application Ser. No. 08/233,310 filed Apr. 26, 1994, whichis a continuation of application Ser. No. 07/888,680 filed May 22, 1992,of P. Wilkinson et al., entitled "Multi-PME Parallel Processor".

These co-pending applications and the present application are owned byone and the same assignee, International Business Machines Corporationof Armonk, N.Y.

The descriptions set forth in these co-pending applications areincorporated into the present application by reference.

CROSS REFERENCE TO OTHER CO-PENDING PATENT APPLICATIONS

Other commonly owned co-pending applications also assigned to the sameassignee as the present application at the time of filing include:

U.S. patent application Ser. No. 07/250,595, filed Sep. 27, 1988, nowabandoned in favor of its continuation application Ser. No. 07/519,332,filed May 4, 1990 of James L. Taylor entitled "SIMD Array Processor"(which was originally published as EPO Application Serial No.88307855/88-A on May 3, 1989); and

U.S. patent application Ser. No. 07/193,990, filed May 13, 1988, of H.Li, entitled "Methods and Circuit for Implementing an Arbitrary Graph ona Polymorphic Mesh"; and

U.S. patent application Ser. No. 07/426,140, filed Oct. 24, 1989, of R.Jaffe et al entitled "Two-Dimensional Input/Output Scheme for MassivelyParallel SIMD Computers"; and

U.S. patent application Ser. No. 07/439,758, filed Nov. 21, 1989, of W.C. Dietrich, Jr. et al entitled "Method and Apparatus for PerformingMemory Protection Operations in a Parallel Processor System"; and

U.S. patent application Ser. No. 07/698,866, filed May 13, 1991, ofDavid B. Rolfe, entitled "Method for Interconnecting and System ofInterconnected Processing Elements".

All above referenced co-pending applications are also are owned by oneand the same assignee, namely, International Business MachinesCorporation of Armonk, N.Y.

The descriptions set forth in these co-pending applications are alsoincorporated by reference.

FIELD OF THE INVENTIONS

The invention relates to computer and computer systems and particularlyto parallel array processors. In accordance with the invention, aparallel array processor (APAP) may be incorporated on a singlesemiconductor silicon chip. This chip forms a basis for the systemsdescribed which are capable of massively parallel processing of complexscientific and business applications.

REFERENCES USED IN THE DISCUSSION OF THE INVENTIONS

In the detailed discussion of the invention, other works will bereferenced, including references to our own unpublished works which arenot Prior Art, which will aid the reader in following the discussion.

GLOSSARY OF TERMS

ALU

ALU is the arithmetic logic unit portion of a processor.

Array

Array refers to an arrangement of elements in one or more dimensions. Anarray can include an ordered set of data items (array element) which inlanguages like Fortran are identified by a single name. In otherlanguages such a name of an ordered set of data items refers to anordered collection or set of data elements, all of which have identicalattributes. A program array has dimensions specified, generally by anumber or dimension attribute. The declarator of the array may alsospecify the size of each dimension of the array in some languages. Insome languages, an array is an arrangement of elements in a table. In ahardware sense, an array is a collection of structures (functionalelements) which are generally identical in a massively parallelarchitecture. Array elements in data parallel computing are elementswhich can be assigned operations and when parallel can eachindependently and in parallel execute the operations required.Generally, arrays may be thought of as grids of processing elements.Sections of the array may be assigned sectional data, so that sectionaldata can be moved around in a regular grid pattern. However, data can beindexed or assigned to an arbitrary location in an array.

Array Director

An Array Director is a unit programmed as a controller for an array. Itperforms the function of a master controller for a grouping offunctional elements arranged in an array.

Array Processor

There two principal types of array processors--multiple instructionmultiple data (MIMD) and single instruction multiple data (SIMD). In aMIMD array processor, each processing element in the array executes itsown unique instruction stream with its own data. In a SIMD arrayprocessor, each processing element in the array is restricted to thesame instruction via a common instruction stream; however, the dataassociated with each processing element is unique. Our preferred arrayprocessor has other characteristics. We call it Advanced Parallel ArrayProcessor, and use the acronym APAP.

Asynchronous

Asynchronous is without a regular time relationship; the execution of afunction is unpredictable with respect to the execution of otherfunctions which occur without a regular or predictable time relationshipto other function executions. In control situations, a controller willaddress a location to which control is passed when data is waiting foran idle element being addressed. This permits operations to remain in asequence while they are out of time coincidence with any event.

BOPS/GOPS

BOPS or GOPS are acronyms having the same meaning--billions ofoperations per second. See GOPS.

Circuit Switched/Store Forward

These terms refer to two mechanisms for moving data packets through anetwork of nodes. Store Forward is a mechanism whereby a data packet isreceived by each intermediate node, stored into its memory, and thenforwarded on towards its destination. Circuit Switch is a mechanismwhereby an intermediate node is commanded to logically connect its inputport to an output port such that data packets can pass directly throughthe node towards their destination, without entering the intermediatenode's memory.

Cluster

A cluster is a station (or functional unit) which consists of a controlunit (cluster controller) and the hardware (which may be terminals,functional units, or virtual components) attached to it. Our Clusterincludes an array of PMEs sometimes called a Node array. Usually acluster has 512 PMEs.

Our Entire PME node array consists of a set of clusters, each clustersupported by a cluster controller (CC).

Cluster controller

A cluster controller is a device that controls input/output (I/O)operations for more than one device or functional unit connected to it.A cluster controller is usually controlled by a program stored andexecuted in the unit as it was in the IBM 3601 Finance CommunicationController, but it can be entirely controlled by hardware as it was inthe IBM 3272 Control Unit.

Cluster synchronizer

A cluster synchronizer is a functional unit which manages the operationsof all or part of a cluster to maintain synchronous operation of theelements so that the functional units maintain a particular timerelationship with the execution of a program.

Controller

A controller is a device that directs the transmission of data andinstructions over the links of an interconnection network; its operationis controlled by a program executed by a processor to which thecontroller is connected or by a program executed within the device.

CMOS

CMOS is an acronym for Complementary Metal-Oxide Semiconductortechnology. It is commonly used to manufacture dynamic random accessmemories (DRAMs). NMOS is another technology used to manufacture DRAMS.We prefer CMOS but the technology used to manufacture the APAP is notintended to limit the scope of the semiconductor technology which isemployed.

Dotting

Dotting refers to the joining of three or more leads by physicallyconnecting them together. Most backpanel busses share this connectionapproach. The term relates to OR DOTS of times past but is used here toidentify multiple data sources that can be combined onto a bus by a verysimple protocol.

Our I/O zipper concept can be used to implement the concept that theport into a node could be driven by the port out of a node or by datacoming from the system bus. Conversely, data being put out of a nodewould be available to both the input to another node and to the systembus. Note that outputting data to both the system bus and another nodeis not done simultaneously but in different cycles.

Dotting is used in the H-DOT discussions where Two-ported PEs or PMEs orPickets can be used in arrays of various organizations by takingadvantage of dotting. Several topologies are discussed including 2D and3D Meshes, Base 2 N-cube, Sparse Base 4 N-cube, and Sparse Base 8N-cube.

DRAM

DRAM is an acronym for dynamic random access memory, the common storageused by computers for main memory. However, the term DRAM can be appliedto use as a cache or as a memory which is not the main memory.

FLOATING-POINT

A floating-point number is expressed in two parts. There is a fixedpoint or fraction part, and an exponent part to some assumed radix orBase. The exponent indicates the actual placement of the decimal point.In the typical floating-point representation a real number 0.0001234 isrepresented as 0.1234-3, where 0.1234 is the fixed-point part and -3 isthe exponent. In this example, the floating-point radix or base is 10,where 10 represents the implicit fixed positive integer base, greaterthan unity, that is raised to the power explicitly denoted by theexponent in the floating-point representation or represented by thecharacteristic in the floating-point representation and then multipliedby the fixed-point part to determine the real number represented.Numeric literals can be expressed in floating-point notation as well asreal numbers.

FLOPS

This terms refers to floating-point instructions per second.Floating-point operations include ADD, SUB, MPY, DIV and often manyothers. Floating-point instructions per second parameter is oftencalculated using the add or multiply instructions and, in general, maybe considered to have a 50/50 mix. An operation includes the generationof exponent, fraction and any required fraction normalization. We couldaddress 32 or 48-bit floating-point formats (or longer but we have notcounted them in the mix.) A floating-point operation when implementedwith fixed point instructions (normal or RISC) requires multipleinstructions. Some use a 10 to 1 ratio in figuring performance whilesome specific studies have shown a ratio of 6.25 more appropriate touse. Various architectures will have different ratios.

Functional unit

A functional unit is an entity of hardware, software, or both, capableof accomplishing a purpose.

Gbytes

Gbytes refers to a billion bytes. Gbytes/s would be a billion bytes persecond.

GIGAFLOPS

(10)**9 floating-point instructions per second.

GOPS and PETAOPS

GOPS or BOPS, have the same meaning--billions of operations per second.PETAOPS means trillions of operations per second, a potential of thecurrent machine. For our APAP machine they are just about the same asBIPs/GIPs meaning billions of instructions per second. In some machinesan instruction can cause two or more operations (ie. both an add andmultiply) but we don't do that. Alternatively it could take manyinstructions to do an op. For example we use multiple instructions toperform 64 bit arithmetic. In counting ops however, we did not elect tocount log ops. GOPS may be the preferred use to describe performance,but there is no consistency in usage that has been noted. One seesMIPs/MOPs then BIPs/BOPs and MegaFLOPS/GigaFLOPS/TeraFLOPS/PetaFlops.

ISA

ISA means the Instruction Set Architecture.

Link

A link is an element which may be physical or logical. A physical linkis the physical connection for joining elements or units, while incomputer programming a link is an instruction or address that passescontrol and parameters between separate portions of the program. Inmultisystems a link is the connection between two systems which may bespecified by program code identifying the link which may be identifiedby a real or virtual address. Thus generally a link includes thephysical medium, any protocol, and associated devices and programming;it is both logical and physical.

MFLOPS

MFLOPS means (10)**6 floating-point instructions per second.

MIMD

MIMD is used to refer to a processor array architecture wherein eachprocessor in the array has its own instruction stream, thus MultipleInstruction stream, to execute Multiple Data streams located one perprocessing element.

Module

A module is a program unit that is discrete and identifiable or afunctional unit of hardware designed for use with other components.Also, a collection of PEs contained in a single electronic chip iscalled a module.

Node

Generally, a node is the junction of links. In a generic array of PEs,one PE can be a node. A node can also contain a collection of PEs calleda module. In accordance with our invention a node is formed of an arrayof PMEs, and we refer to the set of PMEs as a node. Preferably a node is8 PMEs.

Node array

A collection of modules made up of PMEs is sometimes referred to as anode array, is an array of nodes made up of modules. A node array isusually more than a few PMEs, but the term encompasses a plurality.

PDE

A PDE is a partial differential equation.

PDE relaxation solution process

PDE relaxation solution process is a way to solve a PDE (partialdifferential equation). Solving PDEs uses most of the super computingcompute power in the known universe and can therefore be a good exampleof the relaxation process. There are many ways to solve the PDE equationand more than one of the numerical methods includes the relaxationprocess. For example, if a PDE is solved by finite element methodsrelaxation consumes the bulk of the computing time. Consider an examplefrom the world of heat transfer. Given hot gas inside a chimney and acold wind outside, how will the temperature gradient within the chimneybricks develop? By considering the bricks as tiny segments and writingan equation that says how heat flows between segments as a function oftemperature differences then the heat transfer PDE has been convertedinto a finite element problem. If we then say all elements except thoseon the inside and outside are at room temperature while the boundarysegments are at the hot gas and cold wind temperature, we have set upthe problem to begin relaxation. The computer program then models timeby updating the temperature variable in each segment based upon theamount of heat that flows into or out of the segment. It takes manycycles of processing all the segments in the model before the set oftemperature variables across the chimney relaxes to represent actualtemperature distribution that would occur in the physical chimney. Ifthe objective was to model gas cooling in the chimney then the elementswould have to extend to gas equations, and the boundary conditions onthe inside would be linked to another finite element model, and theprocess continues. Note that the heat flow is dependent upon thetemperature difference between the segment and its neighbors. It thususes the inter-PE communication paths to distribute the temperaturevariables. It is this near neighbor communication pattern orcharacteristic that makes PDE relation very applicable to parallelcomputing.

PICKET

This is the element in an array of elements making up an arrayprocessor. It consists of: data flow (ALU REGS), memory, control, andthe portion of the communication matrix associated with the element. Theunit refers to a 1/nth of an array processor made up of parallelprocessor and memory elements with their control and portion of thearray intercommunication mechanism. A picket is a form of processormemory element or PME. Our PME chip design processor logic can implementthe picket logic described in related applications or have the logic forthe array of processors formed as a node. The term PICKET is similar tothe commonly used array term PE for processing element, and is anelement of the processing array preferably comprised of a combinedprocessing element and local memory for processing bit parallel bytes ofinformation in a clock cycle. The preferred embodiment consisting of abyte wide data flow processor, 32k bytes or more of memory, primitivecontrols and ties to communications with other pickets.

The term "picket" comes from Tom Sawyer and his white fence, although itwill also be understood functionally that a military picket line analogyfits quite well.

Picket Chip

A picket chip contains a plurality of pickets on a single silicon chip.

Picket Processor system (or Subsystem)

A picket processor is a total system consisting of an array of pickets,a communication network, an I/O system, and a SIMD controller consistingof a microprocessor, a canned routine processor, and a micro-controllerthat runs the array.

Picket Architecture

The Picket Architecture is the preferred embodiment for the SIMDarchitecture with features that accommodate several diverse kinds ofproblems including:

set associative processing

parallel numerically intensive processing

physical array processing similar to images

Picket Array

A picket array is a collection of pickets arranged in a geometric order,a regular array.

PME or processor memory element

PME is used for a processor memory element. We use the term PME to referto a single processor, memory and I/O capable system element or unitthat forms one of our parallel array processors. A processor memoryelement is a term which encompasses a picket. A processor memory elementis 1/nth of a processor array which comprises a processor, itsassociated memory, control interface, and a portion of an arraycommunication network mechanism. This element can have a processormemory element with a connectivity of a regular array, as in a picketprocessor, or as part of a subarray, as in the multi-processor memoryelement node we have described.

Routing

Routing is the assignment of a physical path by which a message willreach its destination. Routing assignments have a source or origin and adestination. These elements or addresses have a temporary relationshipor affinity. Often, message routing is based upon a key which isobtained by reference to a table of assignments. In a network, adestination is any station or network addressable unit addressed as thedestination of information transmitted by a path control address thatidentifies the link. The destination field identifies the destinationwith a message header destination code.

SIMD

A processor array architecture wherein all processors in the array arecommanded from a Single Instruction stream to execute Multiple Datastreams located one per processing element.

SIMDMIMD or SIMD/MIMD

SIMDMIMD or SIMD/MIMD is a term referring to a machine that has a dualfunction that can switch from MIMD to SIMD for a period of time tohandle some complex instruction, and thus has two modes. The ThinkingMachines, Inc. Connection Machine model CM-2 when placed as a front endor back end of a MIMD machine permitted programmers to operate differentmodes for execution of different parts of a problem, referred tosometimes a dual modes. These machines have existed since Illiac andhave employed a bus that interconnects the master CPU with otherprocessors. The master control processor would have the capability ofinterrupting the processing of other CPUs. The other CPUs could runindependent program code. During an interruption, some provision must bemade for checkpointing (closing and saving current status of thecontrolled processors).

SIMIMD

SIMIMD is a processor array architecture wherein all processors in thearray are commanded from a Single Instruction stream, to executeMultiple Data streams located one per processing element. Within thisconstruct, data dependent operations within each picket that mimicinstruction execution are controlled by the SIMD instruction stream.

This is a Single Instruction Stream machine with the ability to sequenceMultiple Instruction streams (one per Picket) using the SIMD instructionstream and operate on Multiple Data Streams (one per Picket). SIMIMD canbe executed by a processor memory element system.

SISD

SISD is an acronym for Single Instruction Single Data.

Swapping

Swapping interchanges the data content of a storage area with that ofanother area of storage.

Synchronous Operation

Synchronous operation in a MIMD machine is a mode of operation in whicheach action is related to an event (usually a clock); it can be aspecified event that occurs regularly in a program sequence. Anoperation is dispatched to a number of PEs who then go off toindependently perform the function. Control is not returned to thecontroller until the operation is completed.

If the request is to an array of functional units, the request isgenerated by a controller to elements in the array which must completetheir operation before control is returned to the controller.

TERAFLOPS

TERAFLOPS means (10)**12 floating-point instructions per second.

VLSI

VLSI is an acronym for very large scale integration (as applied tointegrated circuits).

Zipper

A zipper is a new function provided. It allows for links to be made fromdevices which are external to the normal interconnection of an arrayconfiguration.

BACKGROUND OF THE INVENTION

In the never ending quest for faster computers, engineers are linkinghundreds, and even thousands of low cost microprocessors together inparallel to create super supercomputers that divide in order to conquercomplex problems that stump today's machines. Such machines are calledmassively parallel. We have created a new way to create massivelyparallel systems. The many improvements which we have made should beconsidered against the background of many works of others.

Multiple computers operating in parallel have existed for decades. Earlyparallel machines included the ILLIAC which was started in the 1960s.ILLIAC IV was built in the 1970s. Other multiple processors include (seea partial summary in U.S. Pat. No. 4,975,834 issued Dec. 4, 1990 to Xuet al) the Cedar, Sigma-1, the Butterfly and the Monarch, the Intelipsc, The Connection Machines, the Caltech COSMIC, the N Cube, IBM'sRP3, IBM's GF11, the NYU Ultra Computer, the Intel Delta and Touchstone.

Large multiple processors beginning with ILLIAC have been consideredsupercomputers. Supercomputers with greatest commercial success havebeen based upon multiple vector processors, represented by the CrayResearch Y-MP systems, the IBM 3090, and other manufacturer's machinesincluding those of Amdahl, Hitachi, Fujitsu, and NEC.

Massively Parallel Processors (MPPs) are now thought of as capable ofbecoming supercomputers. These computer systems aggregate a large numberof microprocessors with an interconnection network and program them tooperate in parallel. There have been two modes of operation of thesecomputers. Some of these machines have been MIMD mode machines. Some ofthese machines have been SIMD mode machines. Perhaps the mostcommercially acclaimed of these machines has been the ConnectionMachines series 1 and 2 of Thinking Machines, Inc.. These have beenessentially SIMD machines. Many of the massively parallel machines haveused microprocessors interconnected in parallel to obtain theirconcurrency or parallel operations capability. Intel microprocessorslike i860 have been used by Intel and others. N Cube has made suchmachines with Intel '386 microprocessors. Other machines have been builtwith what is called the "transputer" chip. Inmos Transputer IMS T800 isan example. The Inmos Transputer T800 is a 32 bit device with anintegral high speed floating point processor.

As an example of the kind of systems that are built, several InmosTransputer T800 chips each would have 32 communication link inputs and32 link outputs. Each chip would have a single processor, a small amountof memory, and communication links to the local memory and to anexternal interface. In addition, in order to build up the systemcommunication link adaptors like IMS C011 and C012 would be connected.In addition switches, like a IMS C004 would provide, say, a crossbarswitch between the 32 link inputs and 32 link outputs to providepoint-to-point connection between additional transputer chips. Inaddition, there will be special circuitry and interface chips fortransputers adapting them to be used for a special purpose tailored tothe requirements of a specific device, a graphics or disk controller.The Inmos IMS M212 is a 16 bit processor, with on chip memory andcommunication links. It contains hardware and logic to control diskdrives and can be used as a programmable disk controller or as a generalpurpose interface. In order to use the concurrency (parallel operations)Inmos developed a special language, Occam, for the transputer.Programmers have to describe the network of transputers directly in anOccam program.

Some of these massively parallel machines use parallel processor arraysof processor chips which are interconnected with different topologies.The transputer provides a crossbar network with the addition of IMS C004chips. Some other systems use a hypercube connection. Others use a busor mesh to connect the microprocessors and there associated circuitry.Some have been interconnected by circuit switch processors that useswitches as processor addressable networks. Generally, as with the 14RISC/6000s which were interconnected last fall at Lawrence Livermore bywiring the machines together, the processor addressable networks havebeen considered as coarse-grained multiprocessors.

Some very large machines are being built by Intel and nCube and othersto attack what are called "grand challenges" in data processing.However, these computers are very expensive. Recent projected costs arein the order of $30,000,000.00 to $75,000,000.00 (Tera Computer) forcomputers whose development has been funded by the U.S. Government toattack the "grand challenges". These "grand challenges" would includesuch problems as climate modeling, fluid turbulence, pollutiondispersion, mapping of the human genome and ocean circulation, quantumchromodynamics, semiconductor and supercomputer modeling, combustionsystems, vision and cognition.

As a footnote to our background, we should recognize one of the earlymassively parallel machines developed by IBM. In our description we havechosen to use the term processor memory element rather than "transputer"to describe one of the eight or more memory units with processor and I/Ocapabilities which make up the array of PMEs in a chip, or node. Thereferenced prior art "transputer" has on a chip one processor, a Fortrancoprocessor, and a small memory, with an I/O interface. Our processormemory element could apply to a transputer and to the PME of the RP3generally. However, as will be recognized, our little chip issignificantly different in many respects. Our little chip has manyfeatures described later. However, we do recognize that the term PME wasfirst coined for another, now more typical, PME which formed the basisfor the massively parallel machine known as the RP3. The IBM ResearchParallel Processing Prototype (RP3) was an experimental parallelprocessor based on a Multiple Instruction Multiple Data (MIMD)architecture. RP3 was designed and built at IBM T. J. Watson ResearchCenter in cooperation with the New York University Ultracomputerproject. This work was sponsored in part by Defense Advanced ResearchProject Agency. RP3 was comprised of 64 Processor-Memory Elements (PMEs)interconnected by a high speed omega network. Each PME contained a32-bit IBM "PC scientific" microprocessor, 32-kB cache, a 4-MB segmentof the system memory, and an I/O port. The PME I/O port hardware andsoftware supported initialization, status acquisition, as well as memoryand processor communication through shared I/O support Processors(ISPs). Each ISP supports eight processor-memory elements through theExtended I/O adapters (ETIOs), independent of the system network. EachISP interfaced to the IBM S/370 channel and the IBM Token-Ring networkas well as providing operator monitor service. Each extended I/O adapterattached as a device to a PME ROMP Storage Channel (RSC) and providedprogrammable PME control/status signal I/O via the ETIO channel. TheETIO channel is the 32-bit bus which interconnected the ISP to the eightadapters. The ETIO channel relied on a custom interface protocol withwas supported by hardware on the ETIO adapter and software on the ISP.

Problems Addressed by our APAP Machine

The machine which we have called the Advanced Parallel Array Processor(APAP) is a fine-grained parallel processor which we believe is neededto address issues of prior designs. As illustrated above, there havebeen many fine-grained (and also coarse-grained) processors constructedfrom both point design and off-the-shelf processors using dedicated andshared memory and any one of the many possible interconnection schemes.To date these approaches have all encountered one or more design andperformance limitations. Each "solution" leads in a different direction.Each has its problems. Existing parallel machines are difficult toprogram. Each is not generally adaptable to various sizes of machinescompatible across a range of applications. Each has its designlimitations caused by physical design, interconnection and architecturalissues.

Physical Issues

Some approaches utilize a separate chip design for each of the variousfunctions required in a horizontal structure. These approaches sufferperformance limitations due to chip crossing delays.

Other approaches integrate various functions together vertically into asingle chip. These approaches suffer performance limitations due to thephysical limit on the number of logic gates which can be integrated ontoa producible chip.

Interconnection Issues

Networks which interconnect the various processing functions areimportant to fine-grained parallel processors. Processor designs withbuses, meshes, and hypercubes have all been developed. Each of thesenetworks has inherent limitations as to processing capability. Buseslimit both the number of processors which can be physicallyinterconnected and the network performance. Meshes lead to large networkdiameters which limit network performance. Hypercubes require each nodeto have a large number of interconnection ports; the number ofprocessors which can be interconnected is limited by the physicalinput/output pins at the node. Hypercubes are recognized as having somesignificant performance gains over the prior bus and mesh structures.

Architectural Issues

Processes which are suitable for fine-grained parallel processors fallinto two distinct types. Processes which are functionally partitionabletend to perform better on multiple instruction, multiple data (MIMD)architectures. Processes which are not functionally partitionable buthave multiple data streams tend to perform better on single instruction,multiple data (SIMD) architectures. For any given application, there islikely to be some number of both types of processes. System trade-offsare required to pick the architecture which best suits a particularapplication but no single solution has been satisfactory.

SUMMARY OF THE INVENTION

We have created a new way to make massively parallel processors andother computer systems by creating a new "chip" and systems designedwith our new concepts. This application is directed to such systems.Components described in our applications can be combined in our systemsto make new systems. They also can be combined with existing technology.

Think, our little CMOS DRAM chip of approximately 14×14 mm can be puttogether much like bricks are walled in a building or paved to form abrick road. Our chip provides the structure necessary to build a"house", a complex computer system, by connected replication.

Placing our development in perspective, four little chips, each onealike, each one with eight or more processors embedded in memory with aninternal array capability and external I/O broadcast and controlinterface, would provide the memory and processing power of thirty-sixor more complex computers, and they could all be placed with compacthybrid packaging into something the size of a watch, and operated withvery low power, as each chip only dissipates about 2 watts. With thischip, we have created many new concepts, and those that we consider ourinvention are described in detail in the description and claims. Thesystems that can be created with our computer system can range fromsmall devices to massive machines with PETAOP potential.

Our little memory chip array processor we call our Advanced ParallelArray Processor. Though small, it is complex and powerful. A typicalcluster will have many chips. Many aspects and features of inventionhave been described in this and related applications. These concepts andfeatures of invention improve and are applicable to computer systemswhich may not employ each invention. We believe our concepts andfeatures will be adopted and used in the next century.

This technical description provides an overview of our Advanced ParallelArray Processor (APAP) representing our new memory concepts and oureffort in developing a scalable massively parallel processor (MPP) thatis simple (very small number of unique part numbers) and has very highperformance. Our processor utilizes in its preferred embodiment a VLSIchip. The chip comprises 2n PME microcomputers. "n" represents themaximum number of array dimensionality. The chip further comprises abroadcast and control interface (BCI) and internal and externalcommunication paths between PMEs on the chip among themselves and to theoff chip system environment. The preferred chip has 8 PMEs (but we alsocan provide more) and one BCI. The 2n PMEs and BCI are considered anode. This node can function in either SIMD or MIMD mode, in dualSIMD/MODE, with asynchronous processing, and with SIMIMD functionality.Since it is scalable, this approach provides a node which can be themain building block for scalable parallel processors of varying size.The microcomputer architecture of the PME provides fully distributedmessage passing interconnection and control features within each node,or chip. Each node provides multiple parallel microcomputer capabilityat the chip level, the microprocesor or personal computer level, at aworkstation level, at special application levels which may berepresented by a vision and/or avionics level, and, when fully extended,to capability at greater levels with powerful Gigaflop performance intothe supercomputer range. The simplicity is achieved by the use of asingle highly extended DRAM Chip that is replicated into parallelclusters. This keeps the part number count down and allows scalingcapability to the cost or performance need, by varying the chip count,then the number of modules, etc.

Our approach enables us to provide a machine with attributes meeting therequirements that drive to a parallel solution in a series ofapplications. Our methods of parallelization at the sub-chip level serveto keep weight, volume, and recurring and logistic costs down.

Because our different size systems are all based upon a single chip,software tools are common for all size systems. This offers thepotential of development software (running on smaller workstationmachines) that is interchangeable among all levels (workstation,aerospace, and supercomputer). That advantage means programmers candevelop programs on workstations while a production program runs on amuch larger machine.

As a result of our well balanced design implementation we meet today'srequirements imposed by technology, performance, cost, and perception,and enable growth of the system into the future. Since our MPP approachstarts at the chip level, our discussion starts at the chip technologydescription and concludes with the supercomputer applicationdescriptions.

Physical, interconnection, and architectural issues will all beaddressed in the machine directly. Functions will not only be integratedinto a single chip design, but the chip design will provide functionssufficiently powerful and flexible that the chip will be effective atprocessing, routing, storage and three classes of I/O. Theinterconnection network will be a new version of the hypercube whichprovides minimum network diameters without the input/output pin andwireability limitations normally associated with hypercubes. Thetrade-off between SIMD and MIMD are eliminated because the design allowsprocessors to dynamically switch between MIMD and SIMD mode. Thiseliminates many problems which will be encountered by applicationprogrammers of "hybrid" machines. In addition, the design will allow asubset of the processors to be in SIMD or MIMD mode.

The Advanced Parallel Array Processor (APAP) is a fine-grained parallelprocessor. It consists of control and processing sections which arepartitionable such that configurations suitable for supercomputingthrough personal computing applications can be satisfied. In mostconfigurations it would attach to a host processor and support the offloading of segments of the host's workload. Because the APAP arrayprocessing elements are general purpose computers, the particular typeof workload off-loaded will vary depending upon the capabilities of thehost. For example, our APAP can be a module for an IBM 3090 vectorprocessor mainframe. When attached to a mainframe with high performancevector floating point capability the task off-loaded might be sparse todense matrix transformations. Alternatively, when attached to a PCpersonal computer the off-loaded task might be numerically intensive 3dimensional graphics processing.

The above referenced parent U.S. Ser. No. 07/611,594, filed Nov. 13,1990 of Dieffenderfer et al., titled "Parallel Associative ProcessorSystem" describes the idea of integrating computer memory and controllogic within a single chip and replicating the combination within thechip and building a processor system out of replications of the singlechip. This approach which is continued and expanded here leads to asystem which provides massively parallel processing capability at thecost of developing and manufacturing only a single chip type whileenhancing performance capability by reducing the chip boundary crossingsand line length.

The above referenced parent U.S. Ser. No. 07/611,594, filed Nov. 13,1990 illustrated utilization of 1-dimensional I/O structures(essentially a linear I/O) with multiple SIMD PMEs attached to thatstructure within a chip. This embodiment elaborates these concepts todimensions greater than 1. The description which follows will be interms of 4-dimensional I/O structures with 8 SIMD/MIMD PMEs per chip.However, that can be extended to greater dimensionality or more PMEs perdimension as we will describe with respect to FIGS. 3, 9, 10, 15 and 16.Our processing element includes a full I/O system including both datatransfer and program Interrupts. Our description of our preferredembodiment will be primarily described in terms of the preferred4-dimensional I/O structures with 8 SIMD/MIMD PMEs per chip, which hasspecial advantages now in our view. However, that can be extended togreater dimensionality or more PMEs per dimension as described in ourparent application. In addition, for most applications we prefer andhave made inventions in areas of greater dimensions with hypercubeinterconnections, preferably with the modified hypercube we describe.However, in some applications a 2-dimensional mesh interconnection ofchips will be applicable to a task at hand. For instance, in certainmilitary computers a 2 dimensional mesh will be suitable and costeffective.

This disclosure extends the concepts from the interprocessorcommunication to the external Input/Output facilities and describes theinterfaces and modules required for control of the processing array. Insummary three types of I/O, Inter-processor, processors to/fromexternal, and broadcast/control are described. Massively parallelprocessing systems require all these types of I/O bandwidth demands tobe balanced with processor computing capability. Within the array theserequirements will be satisfied by replicating a 16 bit (reduced)instruction set processor, augmented with very fast interrupt stateswapping capability. That processor is referred to as the PMEillustrating the preferred embodiment of our APAP. The characteristicsof the PME are completely unique when compared with the processingelements on other massively parallel machines. It permits theprocessing, routing, storage and I/O to be completely distributed. Thisis not characteristic of any other design.

In a hypercube each PME can address as its neighbor, any PME whoseaddress differs in any single bit position. In a ring, any PME canaddress as its neighbor the two PMEs whose addresses differ ±1. Themodified hypercube of our preferred embodiment utilized for the APAPcombines these approaches by building hypercubes out of rings. Theintersection of rings is defined to be a node. Each node of ourpreferred system has its PME, memory and I/O, and other features of thenode, formed in a semiconductor silicon low level CMOS DRAM chip. Nodesare constructed from multiple PMEs on each chip. Each PME exists in onlyone ring of nodes. PMEs within the node are connected by additionalrings such that communications can be routed between rings within thenode. This leads to the addressing structure where any PME can stepmessages toward the objective by addressing a PME in its own ring or anadjacent PME within the node. In essence a PME can address a PME whoseaddress differs by 1 in one in the In₂ d bit field of its ring (where dis the number of PMEs in the ring) or the PME with the same address butexisting in an adjacent dimension. The PME effectively appears to existin n sets of rings, while in actuality it exists only in one real ringand one hidden ring totally contained within the chip. Thedimensionality for the modified hypercube is defined to be the value nfrom the previous sentence.

We prefer to use a modified hypercube. This is elaborated in the part ofthis application describing the technology. Finally, PMEs within a ringare paired such that one moves data externally clockwise along a ring ofnodes and the other moves data externally counterclockwise along thering of nodes, thus dedicating a PME to an external port.

In our massively parallel machine, in our preferred embodiment, theinterconnection and broadcast of data and instructions from one PME toanother PME in the node and externally of the node to other nodes of acluster or PMEs of a massively parallel processing environment areperformed by a programmable router, allowing reconfiguration and virtualflexibility to the network operations. This important feature is fullydistributed and embedded in the PME and allows for processorcommunication and data transfers among PMEs during operations of thesystem in SIMD and MIMD modes, as well as in the SIMD/MIMD and SIMIMDmodes of operation.

Within the rings each interconnection leg is a point-to-pointconnection. Each PME has a point-to-point connection with the twoneighboring PMEs in its ring and with two neighboring PMEs in twoadjacent rings. Three of these point-to-point connections are internalto the node, while the fourth point-to-point connection is to anadjacent node.

The massively parallel processing system uses the processing elements,with their local memory and interconnect topology to connect allprocessors to each other. Embedded within the PME is our fullydistributed I/O programmable router. Our system also provides anaddition to the system which provides the ability to load and unload allthe processing elements. With our zipper we provide a method for loadingand unloading of the array of PEs and thus enable implementation of afast I/O along an edge of the array's rings. To provide for externalinterface I/O any subset of the rings may be broken (un-zipped acrosssome dimension(s)) with the resultant broken paths connected to theexternal interface. The co-pending application entitled "APAP I/OZIPPER", filed concurrently herewith, U.S. Ser. No. 887,612 filed May22, 1992, describes our `zipper` in additional detail. The `zipper` canbe applied to only the subset of links required to support the peakexternal I/O load, which in all configurations considered so far leadsto its being applied only to one or two edges of the physical design.

The final type of I/O consists of data that must be broadcast to, orgathered from all PMEs, plus data which is too specialized to fit on thestandard buses. Broadcast data includes commands, programs and data.Gathered data is primarily status and monitor functions while diagnosticand test functions are the specialized elements. Each node, in additionto the included set of PMEs, contains one Broadcast and ControlInterface (BCI) section.

Consider PMEs interconnected in a modified 4 dimensional hypercubenetwork. If each ring contains 16 PMEs, then the system will have 32,768PMEs. The network diameter is 19 steps. Each PME contains in S/W therouter and reconfiguration S/W to support a particular outgoing port.Thus, software routing provides the capability to reconfigure in theevent of a faulty processing element or node. Inherent in a 4d, 25 Mhznetwork design with byte wide half duplex rings is the provision for 410gigabytes per second peak internal bandwidth.

The 4 dimensional hypercube leads to a particularly advantageouspackage. Eight of the PMEs (including data flow, memory and I/O pathsand controls) are encompassed in a single chip. Thus, a node will be asingle chip including pairs of elements along the rings. The nodes areconfigured together in an 8×8 array to make up a cluster. The fullypopulated machine is built up of an array of 8×8 clusters to provide themaximum capacity of 32,768 PMEs.

Each PME is a powerful microcomputer having significant memory and I/Ofunctions. There is multibyte data flow within a reduced instruction set(RISC) architecture. Each PME has 16 bit internal data flow and eightlevels of program interrupts with the use of working and generalregisters to manage data flow. There is a circuit switched and store andforward mode for I/O transfer under PME software control. The SIMD modeor MIMD mode is under PME software control. The PME can execute RISCinstructions from either the BCI in a SIMD mode, or from its own mainmemory in MIMD mode. Specific RISC instruction code points can bereinterpreted to perform unique functions in the SIMD mode. Each PME canimplement an extended Instruction Set Architecture and provide routingswhich perform macro level instructions such as extended precision fixedpoint arithmetic, floating point arithmetic, vector arithmetic, and thelike. This permits not only complex math to be handled but imageprocessing activities for display of image data in multiple dimensions(2d and 3d images) and for multimedia applications. The system canselect groups of PMEs for a function. PMES assigned can allocateselected data and instructions for group processing. The operations canbe externally monitored via the BCI. Each BCI has a primary controlinput, a secondary control input, and a status monitor output for thenode. Within a node the 2n PMEs can be connection for a binary hypercubecommunication network within the chip. Communication between PMEs iscontrolled by the bits in PME control registers under control of PMEsoftware. This permits the system to have a virtual routing capability.Each PME can step messages up or down its own right or to itsneighboring PME in either of two adjacent rings. Each interface betweenPMEs is a point-to-point connection. The I/O ports permit off-chipextensions of the internal ring to adjacent nodes of the system. Thesystem is built up of replications of a node to form a node array, acluster, and other configurations.

To complement our system's SIMD, MIMD, SIMD/MIMD and SIMIMDfunctionality, our development we have provided unique operationalmodes. Among our SIMD/MIMD PME's unique modes are the new functionalfeatures referred to as the "store and forward/circuit switch"functions. These hardware functions complemented with the on chipcommunication and programmable internal and external I/O routingprovides the PME with very optimal data transferring capability. Inpreferred mode of operation the processor memory is generally the datasink for messages and data targeted at the PME in the store and forwardmode. Messages and data not targeted for the PME are sent directly tothe required output port when in circuit switched mode. The PME softwareperforms the selected routing path while giving the PME a dynamicallyselectable store and forward/circuit switch functionality.

Among the advances we have provided is a fully distributed architecturefor PMEs of a node. Each node has 2n processors, memory and I/O. EveryPME will provide very flexible processing capability with 16 bit dataflow, 64K bytes of local storage, store and forward/circuit switchlogic, PME to PME communication, SIMD/MIMD switching capabilities,programmable routing, and dedicated floating point assist logic. Theorganization of every PME and its communication paths with other PMEswithin the same chip to minimize chip crossing delays. PME functions canbe independently operated by the PME and integrated with functions inthe node, a cluster, and larger arrays.

Our massively parallel system is made up of nodal building blocks ofmultiprocessor nodes, clusters of nodes, and arrays of PMEs alreadypackaged in clusters. For control of these packaged systems whe providea system array director which with the hardware controllers performs theoverall Processing Memory Element (PME) Array Controller functions inthe massively parallel processing environment. The Director comprises ofthree functional areas, the Application Interface, the ClusterSynchronizer, and normally a Cluster Controller. The Array Director willhave the overall control of the PME array, using the broadcast bus andour zipper connection to steer data and commands to all of the PMEs. TheArray Director functions as a software system interacting with thehardware to perform the role as the shell of the APAP operating system.

The interconnection for our PMEs for a massively parallel array computerSIMD/MIMD processing memory element (PME) interconnection provides theprocessor to processor connection in the massively parallel processingenvironment. Each PME utilizes our fully distributed interprocessorcommunication hardware from the on-chip PME to PME connection, to theoff-chip I/O facilities which support the chip-to-chip interconnection.Our modified topology limits our cluster to cluster wiring whilesupporting the advantages of hypercube connections.

The concepts which we employ for a PME node are related to the VLSIpackaging techniques used for the Advanced Parallel Array Processor(APAP) computer system disclosed here, which packaging features of ourinvention provide enhancements to the manufacturing ability of the APAPsystem. These techniques are unique in the area of massively parallelprocessor machines and will enable the machine to be packaged andconfigured in optimal subsets that can be built and tested.

The packaging techniques take advantage of the eight PMEs packaged in asingle chip and arranged in a N-dimensional modified hypercubeconfiguration. This chip level package or node of the array is thesmallest building block in the APAP design. These nodes are thenpackaged in an 8×8 array where the +-X and the +-Y makes rings withinthe array or cluster and the +-W, and +-Z are brought out to theneighboring clusters. A grouping of clusters make up an array. Theintended applications for APAP computers depend upon the particularconfiguration and host. Large systems attached to mainframes witheffective vectorized floating point processors might address specialvectorizable problems--such as weather prediction, wind tunnelsimulation, turbulent fluid modeling and finite element modeling. Wherethese problems involve sparse matrices, significant work must be done toprepare the data for vectorized arithmetic and likewise to storeresults. That workload would be off loaded to the APAP. In intermediatesize systems, the APAP might be dedicated to performing the graphicsoperations associated with visualization, or with some preprocessingoperation on incoming data (i.e., performing optimum assignment problemsin military sensor fusion applications). Small systems attached toworkstations or PCs might serve as programmer development stations ormight emulate a vectorized floating point processor attachment or a 3dgraphics processor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a parallel processor processing element like those whichwould utilize old technology.

FIG. 2 shows a massively parallel processor building block in accordancewith our invention, representing our new chip design.

FIG. 3 illustrates on the right side the preferred chip physical clusterlayout for our preferred embodiment of a chip single node fine grainedparallel processor. There each chip is a scalable parallel processorchip providing 5 MIPs performance with CMOS DRAM memory and logicpermitting air cooled implementation of massive concurrent systems. Onthe left side of FIG. 3, there is illustrated the replaced technology.

FIG. 4 shows a computer processor functional block diagram in accordancewith the invention.

FIG. 5 shows a typical Advanced Parallel Array Processor computer systemconfiguration.

FIG. 6 shows a system overview of our fine-grained parallel processortechnology in accordance with our invention, illustrating system buildup using replication of the PME element which permits systems to bedeveloped with 40 to 193,840 MIPS performance.

FIG. 7 illustrates the hardware for the processing element (PME) dataflow and local memory in accordance with our invention, while

FIG. 8 illustrates PME data flow where a processor memory element isconfigured as a hardwired general purpose computer that provides about 5MIPS fixed point processing or 0.4 MflopS via programmed controlfloating point operations.

FIG. 9 shows the PME to PME connection (binary hypercube) and data pathsthat can be taken in accordance with our invention, while

FIG. 10 illustrates node interconnections for the chip or node which has8 PMEs, each of which manages a single external port and permitsdistribution of the network control function and eliminates a functionalhardware port bottleneck.

FIG. 11 is a block diagram of a scalable parallel processor chip whereeach PME is a 16 bit wide processor with 32K words of local memory andthere is I/O porting for a broadcast port which provides acontroller-to-all interface while external ports are bi-directionalpoint-to-point interfaces permitting ring torus connections within thechip and externally.

FIG. 12 shows an array director in the preferred embodiment.

FIG. 13 in part (a) illustrates the system bus to or from a clusterarray coupling enabling loading or unloading of the array by connectingthe edges of clusters to the system bus (see FIG. 14). In FIG. 13 inpart (b) there is the bus to/from the processing element portion. FIG.13 illustrates how multiple system buses can be supported with multipleclusters. Each cluster can support 50 to 57 Mbyte/s bandwidth.

FIG. 14 shows a "zipper" connection for fast I/O connection.

FIG. 15 shows an 8 degree hypercube connection illustrating a packagingtechnique in accordance with our invention applicable to an 8 degreehypercube.

FIG. 16 shows two independent node connections in the hypercube.

FIG. 17 shows the Bitonic Sort algorithm as an example to illustrate theadvantages of the defined SIMD/MIMD processor system.

FIG. 18 illustrates a system block diagram for a host attached largesystem with one application processor interface illustrated. Thisillustration may also be viewed with the understanding that ourinvention may be employed in stand alone systems which use multipleapplication processor interfaces. Such interfaces in a FIG. 18configuration will support DASD/Graphics on all or many clusters.Workstation accelerators can eliminate the host, application processorinterface (API) and cluster synchronizer (CS) illustrated by emulation.The CS is not required in all instances.

FIG. 19 illustrates the software development environment for our system.Programs can be prepared by and executed from the host applicationprocessor. Both program and machine debug is supported by theworkstation based console illustrated here and in FIG. 22. Both of theseservices will support applications operating on a real or a simulatedMMP, enabling applications to be developed at a workstation level aswell as on a supercomputer formed of the APAP MMP. The common softwareenvironment enhances programmability and distributed usage.

FIG. 20 illustrates the programming levels which are permitted by thenew systems. As different users require more or less detailed knowledge,the software system is developed to support this variation. At thehighest level the user does not need to know the architecture is indeedan MMP. The system can be used with existing language systems forpartitioning of programs, such as parallel Fortran.

FIG. 21 illustrates the parallel Fortran complier system for the MMPprovided by the APAP configurations described. A sequential to parallelcompiler system uses a combination of existing compiler capability withnew data allocation functions and enables use of a partitioning programlike FortranD.

FIG. 22 illustrates the workstation application of the APAP, where theAPAP becomes a workstation accelerator. Note that the unit has the samephysical size as a RISC/6000 Model 530, but this model now contains anMMP which is attached to the workstation via a bus extension moduleillustrated.

FIG. 23 illustrates an application for an APAP MMP module for an AWACSmilitary or commercial application. This is a way of handlingefficiently the classical distributed sensor fusion problem shown inFIG. 23, where the observation to track matching is classically donewith well know algorithms like nearest neighbor, 2 dimensional linearassignment (Munkes..), probabilistic data association or multiplehypothesis testing, but these can now be done in an improved manner asillustrated by FIGS. 24 and 25.

FIG. 24 illustrates how the system provides the ability to handlen-dimensional assignment problems in real time.

FIG. 25 illustrates processing flow for an n-dimensional assignmentproblem utilizing an APAP.

FIG. 26 illustrates the expansion unit provided by the system enclosuredescribed showing how a unit can provide 424 MflopS or 5120 MIPS usingonly 8 to 10 extended SEM-E modules, providing the performancecomparable to that of specialized signal processor module in only 0.6cubic feet. This system can become a SIMD massive machine with 1024parallel processors performing two billion operations per second (GOPS)and can grow by adding 1024 additional processors and 32 MB additionalstorage.

FIG. 27 illustrates the APAP packaging for a supercomputer. Here is alarge system of comparable performance but much smaller footprint thanother systems. It can be built by replicating the APAP cluster within anenclosure like those used for smaller machines.

We have provided, as part of the description, Tables illustrating thehardwired instructions for a PME, in which Table 1 illustratesFixed-point arithmetic instructions; Table 2 illustrates storage tostorage instructions; Table 3 illustrates logical instructions; Table 4illustrates shift instructions; Table 5 illustrates branch instructions;Table 6 illustrates the status switching instructions; and Table 7illustrates the input/output instructions.

(Note: For convenience of illustration in the formal patent drawings,FIGURES may be separated in parts and as a convention we place the topof the FIGURE as the first sheet, with subsequent sheets proceeding downand across when viewing the FIGURE, in the event that multiple sheetsare used.)

Our detailed description follows with parts explaining the preferredembodiments of our invention provided by way of example.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to our invention in greater detail, it will be seen fromFIG. 1, which illustrates the existing technology level, illustrated bythe transputer T800 chip, and representing similar chips for suchmachines as the illustrated by the Touchstone Delta (i860), N Cube('386), and others. When FIG. 1 is compared with the developments here,it will be seen that not only can systems like the prior systems besubstantially improved by employing our invention, but also new powerfulsystems can be created, as we will describe. FIG. 1's conventionalmodern microprocessor technology consumes pins and memory. Bandwidth islimited and inter-chip communication drags the system down.

The new technology leapfrog represented by FIG. 2 merges processors,memory, I/O into multiple PMEs (eight or more 16 bit processors each ofwhich has no memory access delays and uses all the pins for networking)formed on a single low power CMOS DRAM chip. The system can make use ofideas of our prior referenced disclosures as well as inventionseparately described in the applications filed concurrently herewith andapplicable to the system we describe here. Thus, for this purpose theyare incorporated herein by reference. Our concepts of grouping,autonomy, transparency, zipper interaction, asynchronous SIMD, SIMIMD orSIMD/MIMD, can all be employed with the new technology, even though tolesser advantage they can be employed in the systems of the priortechnology and in combination with our own prior multiple picketprocessor.

Our picket system can employ the present processor. Our basic concept isthat we have now provided a replicable brick, a new basic building blockfor systems with our new memory processor, a memory unit having embeddedprocessors, router and I/O. This basic building block is scalable. Thebasic system which we have implemented employs a 4 Meg. CMOS DRAM. It isexpandable to be used in larger memory configurations, with 16 MbitDRAMS, and 64 Mbit chips by expansion. Each processor is a gate array.With denser deposition, many more processors, at higher clock speeds,can be placed on the same chip, and using gates and additional memorywill expand the performance of each PME. Scaling a single part typeprovides a system framwork and architecture which can have a performancewell into the PETAOP range.

FIG. 2 illustrates the memory processor which we call the PME orprocessor memory element in accordance with our preferred embodiment.The processor has eight or more processors. In the pictured embodimentthere are eight. The chip can be expanded (horizontally) to add moreprocessors. The chip can, as preferred, retain the logic and expand theDRAM memory with additional cells linearly (vertically). Pictured are16-32k by 9 bit sections of DRAM memory surrounding a field of CMOS gatearray gates which implement 8 replications of a 16 bit wide data flowprocessors.

Using IBM CMOS low power sub-micron IBM CMOS deposition on silicontechnology, it uses selected silicon with trench to provide significantstorage on a small chip surface. Our memory and multiple processorsorganized interconnect is made with IBM's advanced art of makingsemiconductor chips. However, it will be recognized that the little chipwe describe has about 4 Meg. memory. It is designed so that as 16 Meg.memory technology becomes stable, when improved yields and methods ofaccommodating defects are certain, our little chip can migrate to largermemory sizes each 9 bits wide without changing the logic. Advances inphoto and X-ray lithography keep pushing minimum feature size to wellbelow 0.5 microns. Our design envisions more progress. These advanceswill permit placement of very large amounts of memory with processing ona single silicon chip.

Our device is a 4 MEG CMOS DRAM believed to be the first general memorychip with extensive room for logic. 16 replications of a 32k by 9-bitDRAM macro make up the memory array. The DRAM has 120K cells itallocates with significant surface area for application logic on thechip, with triple level metal wiring. The processor logic cells arepreferably gate array cells. The 35 ns or less DRAM access time matchesthe processor cycle time. This CMOS implementation provides logicdensity for a very effective PE (picket) and does so while dissipating1.3 watts for the logic. The separate memory section of the chip, each32K by 9 bits, (with expansion not changing logic) surrounds the fieldof CMOS gate array gates representing 120K cells, and having the logicdescribed in other figures. Memory is barriered and with a separatedpower source dissipates 0.9 watts. In providing the combining ofsignificant amounts of logic on the same silicon substrate withsignificant amounts of memory problems involved with the electricalnoise incompatibility of logic and DRAM have been overcome. Logic tendsto be very noisy while memory needs relative quiet to sense themillivolt size signals that result from reading the cells of DRAM. Weprefer to provide trenched triple metal layer silicon deposition, withseparate barriered portions of the memory chip devoted to memory and toprocessor logic with voltage and ground isolation, and separate powerdistribution and barriers, to achieve compatibility between logic andDRAM.

APAP System Overview of Preferred Embodiments

This description introduces the new technology in the following order:

1. Technology

2. Chip H/W description

3. Networking and system build up

4. Software

5. Applications

The initial sections of the detailed description describe how 4-Meg DRAMlow power CMOS chips are made to include 8 processors on and as part ofthe manufactured PME DRAM chips each supporting:

1. 16 bit, 5 MIP dataflows,

2. independent instruction stream and interrupt processing and

3. 8 bit (plus parity and controls) wide external port andinterconnection to 3 other on chip processors.

Our invention provides multiple functions which are integrated into asingle chip design. The chip will provide PME functions which arepowerful and flexible and sufficiently so such that a chip havingscalability will be effective at processing, routing, storage and threeclasses of I/O. This chip has integrated memory and control logic withinthe single chip to make the PME, and this combination is replicatedwithin the chip. A processor system is built from replications of thesingle chip.

The approach partitions the low power CMOS DRAM. It will be formed asmultiple word length (16) bit by 32K sections, associating one sectionwith a processor. (We use the term PME to refer to a single processor,memory and I/O capable system unit.) This partitioning leads to eachDRAM chip being an 8 way `cube connected` MIMD parallel processor with 8byte wide independent interconnection ports. (See FIG. 6 for anillustration of a replication of fine-grained parallel technology,illustrating replication and the ring torus possibilities.)

The software description addresses several distinct program types. Atthe lowest level, processes interface the user's program (or servicescalled by the application) to the detailed hardware H/W needs. Thislevel includes the tasks required to manage the I/O and interprocessorsynchronization and is what might be called a microprogram for the MPP.An intermediate level of services provide for both mapping applications(developed with vector or matrix operations) to the MPP, and alsocontrol, synchronization, startup, diagnostic functions. At the hostlevel, high order languages are supported by library functions thatsupport vectorized programs with either simple automatic data allocationto the MPP or user tuned data allocation. The multi-level software S/Wapproach permits applications to exploit different degrees of controland optimization within a single program. Thus, a user can codeapplication programs without understanding the architecture detail whilean optimizer might tune at the microcode level only the small high usagekernels of a program.

Sections of our description that describe 1024 element 5 GIPS units anda 32,768 element 164 GIPS unit illustrate the range of possible systems.However, those are not the limits; both smaller and larger units arefeasible. These particular sizes have been selected as examples becausethe small unit is suitable to microprocessors (accelerators), personalcomputers, workstation and military applications (using of coarsedifferent packaging techniques), while the larger unit is illustrativeof a mainframe application as a module or complete supercomputer system.A software description will provide examples of other challenging workthat might be effectively programmed on each of the illustrativesystems.

PME DRAM CMOS--A BASE FOR A MULTIPROCESSOR PME

FIG. 2 illustrates our technology improvement at the chip technologylevel. This extendable computer organization is very cost andperformance efficient over the wide range of system sizes because ituses only one chip type. Combining the memory and processing on one chipeliminates the pins dedicated to the memory bus and their associatedreliability and performance penalties. Replication of our design withinthe chip makes it economically feasible to consider custom logic designsfor processor subsections. Replication of the chip within the systemleads to large scale manufacturing economies. Finally, CMOS technologyrequires low power per MIP, which in turn minimizes power supply andcooling needs. The chip architecture can be programmed for multiple wordlengths enabling operations to be performed that would otherwise requiremuch larger length processors. In combination these attributes permitthe extensive range of system performance.

Our new technology can be compared with a possible extension of the oldtechnology it overlaps. It is apparent that the advantages of smallerfeatures have been used by processor designers to construct more complexchips and by memory designers to provide greater replication of thesimple element. If the trend continues one could expect memories to getfour times as large while processors might exploit density to:

1. include multiple execute units with instruction routers,

2. increase cache sizes and associative capability and/or

3. increase instruction look ahead and advance computation capability.

However, these approaches to the old technology illustrated by FIG. 1all tend to dead end. Duplicating processors leads to linearlyincreasing pin requirements but pins per chip is fixed. Better cache-ingcan only exploit the application's data reuse pattern. Beyond that,memory bandwidth becomes the limit. Application data dependencies andbranching limit the potential advantage of look ahead schemes.Additionally, it is not apparent that MPP applications with fine-grainedparallelism need 1, 4, or 16 Megaword memories per processing unit.Attempting to share such large memories between multiple processorsresults in severe memory bandwidth limitations.

Our new approach is not dead ended. We combine both significant memoryand I/O and processor into a single chip, as illustrated by the FIG. 2and subsequent illustration and description. It reduces part numberrequirements and eliminates the delays associated with chip crossing.More importantly, this permits all the chip's I/O pins to be dedicatedto interprocessor communication and thus, maximizes network bandwidth.

To implement our preferred embodiment illustrated in FIG. 2 we use aprocess that is available now, using IBM low power CMOS technology. Ourillustrated embodiment can be made with CMOS DRAM density, in CMOS andcan be implemented in denser CMOS. Our illustrated embodiment of 32Kmemory cells for each of 8 PMEs on a chip can be increased as CMOSbecomes denser. In our embodiment we utilize the real estate and processtechnology for a 4 MEG CMOS DRAM, and expand this with processorreplication associated with 32K memory on the chip itself. The chip, itwill be seen has processor, memory, and I/O in each of the chip packagesof the cluster shown in FIG. 3. Within each package is a memory withembedded processor element, router, and I/O, all contained in a 4 MEGCMOS DRAM believed to be the first general memory chip with extensiveroom for logic. It uses selected silicon with trench to providesignificant storage on a small chip surface. Each processor chip of ourdesign alternatively can be made with 16 replications of a 32K by 9 bitDRAM macro (35/80 ns) using 0.87 micron CMOS logic to make up the memoryarray. The device is unique in that it allocates surface area for 120Kcells of application logic on the chip, supported by the capability oftriple level metal wiring. The multiple cards of the old technology isshown crossed out on the left side of FIG. 3.

Our basic replicable element brick technology is an answer to the oldtechnology. If one considered the "Xed" technology on the left of FIG.3, one would see too many chips, too many cards, and waste. For example,today's proposed teraflop machines that others offer would haveliterally a million or more chips in them. With todays other technologyonly a few percent of these chips, at best, are truly operationsproducers. The rest are "overhead" (typically memory, network interface,etc.).

It will become evident that it is not feasible to package such chips, insuch a large number, in anything that must operate in a constrainedenvironment of physical size. (How many could you fit in a small area ofa cockpit?) Furthermore, such proposed teraflop machines of others,already huge, must scale up 1000× times to reach the petaop range. Wehave a solution which dramatically decreases the percent ofnon-operations producting chips. We provide increased bandwidth. Weprovide this within a reasonable network dimensionality. With such abrick technology, where memory becomes the operator, and networks areused for passing controls, where operations producing chips aredramatically increased. In addition, the upgrade dramatically reducesthe number of different types of chips. Our system is designed forscale-up, without a requirement for specialized packaging, cooling,power, or environmental constraints.

With our brick technology, utilizing instead of separate processors,memory units with built in processors and network capability, theconfiguration shown in FIG. 3, representing a card, with chips which arepin comparable with current 4Mbit DRAM cards at the connector level.Such a single card could hold, with a design point of a basic 40 mip perchip performance level, 32 chips, or 1280 mips. Four such cards wouldprovide 5 gips. The workstation configuration which is illustrated woupdpreferably have such a PE memory array, a cluster controller, and an IBMRISC System/6000 which has sufficient performance to run and monitorexecution of an array processor application developed at theworkstation.

A very gate efficient processor can be used in the processor portion.Such designs for processors have been employed, but never within memory.Indeed, in addition, we have provided the ability to mix MIMD and SIMDbasic operation provisions. Our chip provides a "broadcast bus" whichprovides an alternate path into each CPU's instruction buffer. Ourcluster controller issues commands to each of the PEs in the PMEs, andthese can be stored in the PME to control their operation in one mode oranother. Each PME does not have to store an entire program, but canstore only those portions applicable to a given task at various timesduring processing of an application.

Given the basic device one can elect to develop a single processormemory combination. Alternatively, by using a more simple processor anda subset of the memory macros one can design for either 2, 4, 8 or 16replications of the basic processing element (PME). The PME can be madesimpler either by adjusting the dataflow bandwidth or by substitutingprocessor cycles for functional accelerators. For most embodiments weprefer to make 8 replications of the basic processing element wedescribe.

Our application studies have indicated that for now the most favorableanswer is 8 replications of a 16 bit wide data flow and 32K word memory.We conclude this because:

1. 16 bit words permit single cycle fetch of instructions and addresses.

2. 8 PMEs each with an external port permits 4 dimensional torusinterconnections. Using 4 or 8 PMEs on each ring leads to modulessuitable for the range of targeted system performances,

3. 8 external ports requires about 50% of the chip pins, providingsufficient remainder for power, ground and common control signals.

4. 8 Processors implemented in a 64 KByte Main Store

a. allows for a register based architecture rather than a memory mappedarchitecture, and it

b. forces some desirable but not required accelerators to be implementedby multiple processor cycles.

This last attribute is important because it permits use of thedeveloping logic density increase. Our new accelerators (ex. floatingpoint arithmetic unit per PME) are added as chip hardware withoutaffecting system design, pins and cables or application code.

The resultant chip layout and size (14.59×14.63 mm) is shown in FIG. 2,and FIG. 3 shows a cluster of such chips, which can be packaged insystems like those shown in later FIGURES for stand alone units,workstations which slide next to a workstation host with a connectionbus, in AWACs applications, and in supercomputers. This chip technologyprovides a number of system level advantages. It permits development ofthe scalable MPP by basic replication of a single part type. The twoDRAM macros per processor provide sufficient storage for both data andprogram. An SRAM of equivalent size might consume more than 10 timesmore power. This advantage permits MIMD machine models rather than themore limited SIMD models characteristic of machines with single chipprocessor/memory designs. The 35 ns or less DRAM access time matches theexpected processor cycle time. CMOS logic provides the logic density fora very effective PME and does so while dissipating only 1.3 watts.(Total chip power is 1.3+0.9 (memory)=2.2 w.) Those features in turnpermit using the chip in MIL applications requiring conduction cooling.(Air cooling in non-MIL applications is significantly easier.) However,the air cooled embodiment can be used for workstation and otherenvironments. A standalone processor might be configured with an 80amp-5 volt power supply.

Advanced Parallel Array Processor (APAP) building blocks are shown inFIG. 4 and in FIG. 5. FIG. 4 illustrates the functional block diagram ofthe Advanced Parallel Array Processor. Multiple application interfaces150, 160, 170, 180 exist for the application processor 100 or processors110, 120, 130. FIG. 5 illustrates the basic building blocks that can beconfigured into different system block diagrams. The APAP, in a maximumconfiguration, can incorporate 32,768 identical PMEs. The processorconsists of the PME Array 280, 290, 300, 310, an Array Director 250 andan Application Processor Interface 260 for the application processor 200or processors 210, 220, 230. The Array Director 250 consists of threefunctional units: Application Processor Interface 260, clusterSynchronizer 270 and cluster Controller 270. An Array Director canperform the functions of the array controller of our prior linear picketsystem for SIMD operations with MIMD capability. The cluster controller270, along with a set of 64 Array clusters 280, 290, 300, 310, (i.e.cluster of 512 PMEs), is the basic building block of the APAP computersystem. The elements of the Array Director 250 permit configuringsystems with a wide range of cluster replications. This modularity basedupon strict replication of both processing and control elements isunique to this massively parallel computer system. In addition, theApplication Processor Interface 260 supports the Test/Debug device 240which will accomplish important design, debug, and monitoring functions.

Controllers are assembled with a well-defined interface, e.g. IBMsMicrochannel, used in other systems today, including controllers withi860 processors. Field programmable gate arrays add functions to thecontroller which can be changed to meet a particular configuration'srequirements (how many PMEs there are, their couplings, etc.)

The PME arrays 280, 290, 300, 310 contain the functions needed tooperate as either SIMD or MIMD devices. They also contain functions thatpermit the complete set of PMEs to be divided into 1 to 256 distinctsubsets. When divided into subsets the Array Director 250 interleavesbetween subsets. The sequence of the interleave process and the amountof control exercised over each subset is program controlled. Thiscapability to operate distinct subsets of the array in one mode, i.e.,MIMD with differing programs, while other sets operate in tightlysynchronized SIMD mode under Array Director control, represents anadvance in the art. Several examples presented later illustrate theadvantages of the concept.

Array Architecture

The set of nodes forming the Array is connected as a n-dimensionalmodified hypercube. In that interconnection scheme, each node has directconnections to 2n other nodes. Those connections can be either simplex,half-duplex or full-duplex type paths. In any dimension greater than 3d,the modified hypercube is a new concept in interconnection techniques.(The modified hypercube in the 2d case generates a torus, and in the 3dcase an orthogonally connected lattice with edge surfaces wrapped toopposing surface.)

To describe the interconnection scheme for greater than 3d casesrequires an inductive description. A set of m₁ nodes can beinterconnected as a ring. (The ring could be `simply connected`,`braided`, `cross connected`, `fully connected`, etc. Althoughadditional node ports are needed for greater than simple rings, thatadded complexity does not affect the modified hypercube structure.) Them₂ rings can then be linked together by connecting each equivalent nodein the m₂ set of rings. The result at this point is a torus. Toconstruct a i+1d modified hypercube from an id modified hypercube,consider m_(i+1) sets of id modified hypercubes and interconnect all ofthe equivalent m_(i) level nodes into rings.

This process is illustrated for the 4d modified hypercube, using m_(i)=8 for i=1 . . . 4 by the illustration in FIG. 6. Compare ourdescription under node Topology and also FIGS. 6, 9, 10, 15 and 16.

FIG. 6 illustrates the fine-grained parallel technology path from thesingle processor element 300, made up of 32K 16-bit words with a 16-bitprocessor to the Network node 310 of eight processors 312 and theirassociated memory 311 with their fully distributed I/O routers 313 andSignal I/O ports 314, 315, on through groups of nodes labeled clusters320 and into the cluster configuration 360 and to the variousapplications 330, 340, 350, 370. The 2d level structure is the cluster320, and 64 clusters are integrated to form the 4d modified hypercube of32,768 Processing Elements 360.

Processing Array Element (PME) Preferred Embodiment

As illustrated by FIG. 2 and FIG. 11 the preferred APAP has a basicbuilding block of a one chip node. Each node contains 8 identicalprocessor memory elements (PMEs) and one broadcast and control interface(BCI). While some of our inventions may be implemented when allfunctions are not on the same chip, it is important from a performanceand cost reduction standpoint to provide the chip as a one chip nodewith the 8 processor memory elements using the advanced technology whichwe have described and can be implemented today.

The preferred implementation of a PME has a 64 KByte main store, 1616-bit general registers on each of 8 program interrupt levels, a fullfunction arithmetic/logic unit (ALU) with working registers, a statusregister, and four programmable bi-directional I/O ports. In additionthe preferred implementation provides a SIMD mode broadcast interfacevia the broadcast and control interface (BCI) which allows an externalcontroller (see our original parent application and the description ofour currently preferred embodiment for a nodal array and system withclusters) to drive PME operation decode, memory address, and ALU datainputs. This chip can perform the functions of a microcomputer allowingmultiple parallel operations to be performed within it, and it can becoupled to other chips within a system of multiple nodes, whether by aninterconnection network, a mesh or hypercube network, or our preferredand advanced scalable embodiment.

The PMEs are interconnected in a series of rings or tori in ourpreferred scalable embodiment. In some applications the nodes could beinterconnected in a mesh. In our preferred embodiment each node containstwo PMEs in each of four tori. The tori are denoted W,X,Y, and Z (seeFIG. 6). FIG. 11 depicts the interconnection of PMEs within a node. Thetwo PMEs in each torus are designated by their external I/O port (+W,-W, +X. -X, +Y, -Y, +Z, -Z). Within the node, there are also two ringswhich interconnect the 4+n and 4-n PMEs. These internal rings providethe path for messages to move between the external tori. Since the APAPcan be in our preferred embodiment a four dimensional orthogonal array,the internal rings allow messages to move throughout the array in alldimensions.

The PMEs are self-contained stored program microcomputers comprising amain store, local store, operation decode, arithmetic/logic unit (ALU),working registers and Input/Output I/O ports. The PMEs have thecapability of fetching and executing stored instructions from their ownmain store in MIMD operation or to fetch and execute commands via theBCI interface in SIMD mode. This interface permits intercommunicationamong the controller, the PME, and other PMEs in a system made up ofmultiple chips.

The BCI is the node's interface to the external array controller elementand to an array director. The BCI provides common node functions such astimers and clocks. The BCI provides broadcast function masking for eachnodal PME and provides the physical interface and buffering for thebroadcast-bus-to-PME data transfers, and also provides the nodalinterface to system status and monitoring and debug elements.

Each PME contains separate interrupt levels to support each of itspoint-to-point interfaces and the broadcast interface. Data is input tothe PME main store or output from PME main store under Direct MemoryAccess (DMA) control. An "input transfer complete" interrupt isavailable for each of the interfaces to signal the PME software thatdata is present. Status information is available for the software todetermine the completion of data output operations.

Each PME has a "circuit switched mode" of I/O in which one of its fourinput ports can be switched directly to ones of its four output ports,without having the data enter the PME main store. Selection of thesource and destination of the "circuit switch" is under control of thesoftware executing on the PME. The other three input ports continue tohave access to PME main store functions, while the fourth input isswitched to an output port.

An additional type of I/O has data that must be broadcast to, orgathered from all PMEs, plus data which is too specialized to fit on thestandard buses. Broadcast data can include SIMD commands, MIMD programs,and SIMD data. Gathered data is primarily status and monitor functions.Diagnostic and test functions are the specialized data elements. Eachnode, in addition to the included set of PMEs, contains one BCI. Duringoperations the BCI section monitors the broadcast interface andsteers/collects broadcast data to/from the addressed PME(s). Acombination of enabling masks and addressing tags are used by the BCI todetermine what broadcast information is intended for which PMEs.

Each PME is capable of operating in SIMD or in MIMD mode in ourpreferred embodiment. In SIMD mode, each instruction is fed into the PMEfrom the broadcast bus via the BCI. The BCI buffers each broadcast dataword until all of its selected nodal PMEs have used it. Thissynchronization provides accommodation of the data timing dependenciesassociated with the execution of SIMD commands and allows asynchronousoperations to be performed by a PME. In MIMD mode, each PME executes itsown program from its own main store. The PMEs are initialized to theSIMD mode. For MIMD operations, the external controller normallybroadcasts the program to each of the PMEs while they are in SIMD mode,and then commands the PMEs to switch to MIMD mode and begin executing.Masking/tagging the broadcast information allows different sets of PMEsto contain different MIMD programs, and/or selected sets of PMEs tooperate in MIMD mode while other sets of PMEs execute in SIMD mode. Invarious software clusters or partitions these separate functions canoperate independently of the actions in other clusters or partitions.

The operation of the Instruction Set Architecture (ISA) of the PME willvary slightly depending on whether the PME is in the SIMD or MIMD mode.Most ISA instructions operate identically regardless of mode. However,since the PME in SIMD mode does not perform branching or other controlfunctions some code points dedicated to those MIMD instructions arereinterpreted in SIMD mode to allow the PME to perform specialoperations such as searching main memory for a match to a broadcast datavalue or switching to MIMD mode. This further extends system flexibilityof an array.

PME Architecture

Basically, our preferred architecture comprises a PME which has a 16 bitwide data flow, 32K of 16 bit memory, specialized I/O ports and I/Oswitching paths, plus the necessary control logic to permit each PME tofetch, decode and execute the 16 bit instruction set provided by ourinstruction set architecture (ISA). The preferred PME performs thefunctions of a virtual router, and thus performs both the processingfunctions and data router functions. The memory organization allows bycross addressing of memory between PMEs access to a large random accessmemory, and direct memory for the PME. The individual PME memory can beall local, or divided into local and shared global areasprogrammatically. Specialized controls and capabilities which wedescribe permit rapid task switching and retention of program stateinformation at each of the PMEs interrupt execution levels. Althoughsome of the capabilities we provide have existed in other processors,their application for management of interprocessor I/O is unique inmassively parallel machines. An example is the integrate of the messagerouter function into the PME itself. This eliminates specialized routerchips or development of specialized VLSI routers. We also recognize thatin some instances one could distribute the functions we provide on asingle chip onto several chips interconnected by metalization layers orotherwise and accomplish improvements to massively parallel machines.Further, as our architecture is scalable from a single node to massivelyparallel supercomputer level machines, it is possible to utilize some ofour concepts at different levels. As we will illustrate for example ourPME data flow is very powerful, and yet operates to make the scalabledesign effective.

The PME processing memory element develops for each of the multiple PMEsof a node, a fully distributed architecture. Every PME will be comprisedof processing capability with 16 bit data flow, 64K bytes of localstorage, store and forward/circuit switch logic, PME to PMEcommunication, SIMD/MIMD switching capabilities, programmable routing,and dedicated floating point assist logic. These functions can beindependently operated by the PME and integrated with other PMEs withinthe same chip to minimize chip crossing delays. Referring to FIGS. 7 and8 we illustrate the PME dataflow. The PME consists of 16 bit widedataflow 425, 435, 445, 455, 465, 32K by 16 bit memory 420, specializedI/O ports 400, 410, 480, 490 and I/O switching paths 425, plus thenecessary control logic to permit the PME to fetch, decode and execute a16 bit reduced instruction set 430, 440, 450, 460. The special logicalso permits the PME to perform as both the processing unit 460 and datarouter. Specialized controls 405, 406, 407, 408 and capabilities areincorporated to permit rapid task switching and retention of programstate information at each of the PMEs' interrupt execution levels. Suchcapabilities have been included in other processors; however, theirapplication specifically for management of interprocessor I/O is uniquein massively parallel machines. Specifically, it permits the integrationof the router function into the PME without requiring specialized chipsor VLSI development macros.

16 Bit Internal Data Flow and Control

The major parts of the internal data flow of the processing element areshown in FIG. 7. FIG. 7 illustrates the internal data flow of theprocessing element. This processing element has a full 16 bit internaldata flow 425, 435, 445, 455, 465. The important paths of the internaldata flows use 12 nanosecond hard registers such as the OP register 450,M register 440, WR register 470, and the program counter PC register430. These registers feed the fully distributed ALU 460 and I/O routerregisters and logic 405, 406, 407, 408 for all operations. With currentVLSI technology, the processor can execute memory operations andinstruction steps at 25 Mhz, and it can build the important elements, OPregister 450, M register 440, WR register 470, and the PC register 430with 12 nanosecond hard registers. Other required registers are mappedto memory locations.

As seen in FIG. 8 the internal data flow of the PME has its 32K by 16bit main store in the form of two DRAM macros. The remainder of the dataflow consists of CMOS gate array macros. All of the memory can be formedwith the logic with low power CMOS DRAM deposition techniques to form anvery large scaled integrated PME chip node. The PME is replicated 8times in the preferred embodiment of the node chip. The PME data flowconsists of a 16 word by 16 bit general register stack, a multi-functionarithmetic/logic unit (ALU) working registers to buffer memoryaddresses, memory output registers, ALU output registers,operation/command, I/O output registers, and multiplexors to selectinputs to the ALU and registers. Current CMOS VLSI technology for 4MByte DRAM memory with our logic permits a PME to execute instructionsteps at 25 Mhz. We are providing the OP register, the M register, theWR register and the general register stack with 12 nanosecond hardregisters. Other required registers are mapped to memory locationswithin a PME.

The PME data flow is designed as a 16 bit integer arithmetic processor.Special multiplexor paths have been added to optimize subroutineemulation of n×16 bit floating point operations (n=>1). The 16 bit dataflow permits effective emulation of floating point operations. Specificpaths within the data flow have been included to permit floating pointoperations in as little as 10 cycles. The ISA includes special codepoint to permit subroutines for extended (longer than 16-bit) operandoperations. The subsequent floating point performance is approximatelyone twentieth the fixed floating point performance. This performance isadequate to eliminate the need for special floating point chipsaugmenting the PME as is characteristic of other massively parallelmachines. Some other processors do include the special floating pointprocessors on the same chip as a single processor (See FIG. 1). We canenable special floating point hardware processors on the same chip withour PMEs but we would now need additional cells than is required for thepreferred embodiment. For floating point operations, see also theconcurrently filed FLOATING POINT application referenced above forimprovements to the IEEE standard.

The approach developed is well poised to take advantage of the normalincreases in VLSI technology performance. As circuit size shrinks andgreater packaging density becomes possible then data flow elements likebase and index registers, currently mapped to memory could be moved tohardware. Likewise, floating point sub-steps are accelerated withadditional hardware which we will prefer for the developing CMOS DRAMtechnology as reliable higher density levels are achieved. Veryimportantly, this hardware alternative does not affect any software.

The PME is initialized to SIMD mode with interrupts disabled. Commandsare fed into the PME operation decode buffer from the BCI. Each time aninstruction operation completes, the PME requests a new command from theBCI. In a similar manner, immediate data is requested from the BCI atthe appropriate point in the instruction execution cycle. Mostinstructions of the ISA operate identically whether the PME is in SIMDmode or in MIMD mode, with the exception of that SIMD instructions andimmediate data are taken from the BCI; in MIMD mode the PME maintains aprogram counter (PC) and uses that as the address within its own memoryto fetch a 16 bit instruction. Instructions such as "Branch" whichexplicitly address the program counter have no meaning in SIMD mode andsome of those code points are reinterpreted to perform special SIMDfunctions as comparing immediate data against an area of main store.

The PME instruction decode logic permits either SIMD/MIMD operationalmodes, and PMEs can transition between modes dynamically. In SIMD modethe PME receives decoded instruction information and executes that datain the next clock cycle. In MIMD mode the PME maintains a programcounter PC address and uses that as the address within its own memory tofetch a 16 bit instruction. Instruction decode and execution proceeds asin most any other RISC type machine. A PME in SIMD mode enters MIMD modewhen given the information that represents a decode branch. A PME inMIMD mode enters the SIMD mode upon executing a specific instruction forthe transition.

When PMEs transition dynamically between SIMD and MIMD modes, an MIMDmode is entered by execution of a SIMD "write control register"instruction with the appropriate control bit set to a "1". At thecompletion of the SIMD instruction, the PME enters the MIMD mode,enables interrupts, and begins fetching and executing its MIMDinstructions from the main store location specified by its generalregister R0. Interrupts are masked or unmasked depending on the state ofinterrupt masks when the MIMD control bit is set. The PME returns toSIMD mode either by being externally reinitialized or by executing aMIMD "write control register" instruction with the appropriate controlbit set to zero.

Data Communication Paths and Control

Returning to FIG. 7 it will be seen that each PME has 3 input ports 400,and 3 output ports 480 intended for on-chip communication plus 1 I/Oport 410, 490 for off chip communications. Existing technology, ratherthan the processor idea, requires that the off-chip port be byte widehalf duplex. Input ports are connected such that data may be routed frominput to memory, or from input AR register 405 to output register 408via direct 16 bit data path 425. Memory would be the data sink formessages targeted at the PME or for messages that were moved in `storeand forward` mode. Messages that do not target the particular PME aresent directly to the required output port, providing a `circuitswitched` mode, when blocking has not occurred. The PME S/W is chargedwith performing the routing and determining the selected transmissionmode. This makes dynamically selecting between `circuited switched` and`store and forward` modes possible. This is also another uniquecharacteristic of the PME design.

Thus, our preferred node has 8 PMEs and each PME has 4 output ports(Left, Right, Vertical, and External). Three of the input ports andthree of the output ports are 16-bit wide full duplex point-to-pointconnections to the other PMEs on the chip. The fourth ports are combinedin the preferred embodiment to provide a half duplex point-to-pointconnection to an off-chip PME. Due to pin and power constraints that wehave imposed to make use of the less dense CMOS we employ, the actualoff-chip interface is a byte-wide path which is used to multiplex twohalves of the inter-PME data word. With special "zipper" circuitry whichprovides a dynamic, temporary logical breaking of intermodal rings toallow data to enter or leave an array, these external PME ports providethe APAP external I/O array function.

For data routed to the PME memory, normal DMA is supported such that thePME instruction stream must become involved in the I/O processing onlyat the beginning and end of messages. Finally, data that is being`circuit switched` to an internal output port is forwarded withoutclocking. This permits single cycle data transfers within a chip anddetects when chip crossings will occur such that the fastest but stillreliable communication can occur. Fast forwarding utilizes forward datapaths and backward control paths, all operating in transparent mode. Inessence, a source looks through several stages to see theacknowledgments from the PME performing a DMA or off-chip transfer.

As seen by FIGS. 7 and 8 Data on a PME input port may be destined forthe local PME, or for a PME further down the ring. Data destined for aPME further down the ring may be stored in the local PME main memory andthen forwarded by the local PME towards the target PME (store andforward), or the local input port may be logically connected to aparticular local output port (circuit switched) such that the datapasses "transparently" through the local PME on its way to the targetPME. Local PME software dynamically controls whether or not the localPME is in "store and forward" mode or in "circuit switched" mode for anyof the four inputs and four outputs. In circuit switched mode, the PMEconcurrently processes all functions except the I/O associated with thecircuit switch; in store and forward mode the PME suspends all otherprocessing functions to begin the I/O forwarding process.

While data may be stored externally of the array in a shared memory orDASD (with external controller), it may be stored anywhere in thememories provided by PMEs. Input data destined for the local PME orbuffered in the local PME during "store and forward" operations isplaced into local PME main memory via a direct memory access (address)mechanism associated with each of the input ports. A program interruptis available to indicate that a message has been loaded into PME mainmemory. The local PME program interprets header data to determine if thedata destined for the local PME is a control message which can be usedto set up a circuit-switched path to another PME, or whether it is amessage to be forwarded to another PME. Circuit switched paths arecontrolled by local PME software. A circuit switched path logicallycouples a PME input path directly to an output path without passingthrough any intervening buffer storage. Since the output paths betweenPMEs on the same chip have no intervening buffer storage, data can enterthe chip, pass through a number of PMEs on the chip and be loaded into atarget PME's main memory in a single clock cycle! Only when a circuitswitch combination leaves the chip, is an intermediate buffer storagerequired. This reduces the effective diameter of the APAP array by anumber of unbuffered circuit switched paths. As a result data can besent from a PME to a target PME in as few clock cycles as there areintervening chips, regardless of the number of PMEs in the path. Thiskind of routing can be compared to a switched environment in which ateach node cycles are required to carry data on to the next node. Each ofour nodes has 8 PMEs!

Memory and Interrupt Levels

The PME contains 32K by 16 bit 420 dedicated storage words. This storageis completely general and can contain both data and program. In SIMDoperations all of memory could be data as is characteristic of otherSIMD massively parallel machines. In MIMD modes, the memory is quitenormal; but, unlike most massively parallel MIMD machines the memory ison the same chip with the PME and is thus, immediately available. Thisthen eliminates the need for cache-ing and cache coherency techniquescharacteristic of other massively parallel MIMD machines. In the casefor instance of Inmos's chip, only 4K resides on the chip, and externalmemory interface bus and pins are required. These are eliminated by us.

Low order storage locations are used to provide a set of general purposeregisters for each interrupt level. The particular ISA developed for thePME uses short address fields for these register references. Interruptsare utilized to manage processing, I/O activities and S/W specifiedfunctions (i.e., a PME in normal processing will switch to an interruptlevel when incoming I/O initiates). If the level is not masked, theswitch is made by changing a pointer in H/W such that registers areaccessed from a new section of low order memory and by swapping a singlePC value. This technique permits fast level switching and permits S/W toavoid the normal register save operations and also to save status withinthe interrupt level registers.

The PME processor operates on one of eight program interrupt levels.Memory addressing permits a partitioning of the lower 576 words ofmemory amoung the eight levels of interrupts. 64 of these 576 words ofmemory are directly addressable by programs executing on any of theeight levels. The other 512 words are partitioned into eight 64 wordsegments. Each 64 word segment is directly accessible only by programsexecuting on its associated interrupt level. Indirect addressingtechniques are employed for allowing all programs to access all 32Kwords of PME memory.

The interrupt levels are assigned to the input ports, the BCI, and toerror handling. There is a "normal" level, but there is no "privileged",nor "supervisor" level. A program interrupt causes a context switch inwhich the contents of the PC program counter, status/control register,and selected general registers are stored in specified main memorylocations and new values for these registers are fetched from otherspecified main memory locations.

The PME data flow discussed with reference to FIGS. 7 and 8. may beamplified by reference to the additional sections below. In a complexsystem, the PME data flow uses the combination of the chip as an arraynode with memory, processor and I/O which sends and receives messageswith the BCI that we replicate as the basic building block of an MMPbuilt with our APAP. The MMP can handle many word lengths.

PME Multiple Length Data Flow Processing

The system we describe can perform the operations handled by currentprocessors with the data flow in the PME which is 16 bits wide. This isdone by performing operations on data lengths which are multiples of 16bits. This is accomplished by doing the operation in 16 bit pieces. Onemay need to know the result of each piece (i.e. was it zero, was there acarry out of the high bits of the sum).

Adding two numbers of 48 bits can be an example of data flow. In thisexample two numbers of 48 bits (a(0-47) and b(0-47)) are added byperforming the following in the hardware:

    a(32-47)+b(32-47)->ans(32-47)--step one

1) save the carry out of high bit of sum

2) remember if partial result was zero or non-zero

    a(16-31)+b(16-31)+save carry->ans(16-31)--step two

1) save the carry out of high bit of sum

2) remember if partial result was zero or non-zero from this result andfrom previous step; if both are zero remember zero; if either isnon-zero remember non-zero

    a(0-15)+b(0-15)+saved carry->ans(0-15)--final step

1) if this piece is zero and last piece was zero ans is zero

2) if this piece is zero and last piece was non-zero ans is non-zero

3) if this piece is non-zero ans is positive or negative based on signof sum (assuming no overflow)

4) if carry into sign of ans os not-equal to carry out of sign ofanswer, ans has wrong sign and result is an overflow (can not properlyrepresent in the available bits)

The length can be extended by repeating the second step in the middle asmany times as required. If the length were 32 the second step would notbe performed. If the length were greater than 48, step two would be donemultiple times. If the length were just 16 the operation in step one,with conditions 3 and 4 of the final step would be done. Extending thelength of the operands to multiple lengths of the data flow is atechnique having a consequence that the instruction usually takes longerto execute for a narrower data flow. That is, a 32 bit add on a 32 bitdata flow only takes one pass through the adder logic, while the sameadd on a 16 bit data flow takes two passes through the adder logic.

What we have done that is interesting is that in the currentimplementation of the machine we have single instructions which canperform adds/subtracts/compares/moves on operands of length 1 to 8 words(length is defined as part of the instruction). Individual instructionsavailable to the programmer perform the same kind of operations as shownabove for steps one, two, and final (except to the programmer theoperand length is longer i.e. 16 to 128 bits). At the bare boneshardware level, we are working on 16 bits at a time, but the programmerthinks s/he's doing 16 to 128 bits at a time.

By using combinations of these instructions, operands of any length canbe manipulated by the programmer i.e. two instructions can be used toadd two numbers of up to 256 bits in length.

PME Processor

Our PME processor is different from modern microprocessors currentlyutilized for MPP applications. The processor portion differencesinclude:

1. the processor is a fully programmable hardwired computer (see the ISAdescription for an instruction set overview) with:

it has a complete memory module shown in the upper right corner (seeFIG. 8),

it has hardware registers with controls required to emulate separateregister sets for each interrupt level (shown in upper left corner),

its ALU has the required registers and controls to permit effectivemulti-cycle integer and floating point arithmetic,

it has I/O switching paths needed to support packet or circuit switcheddata movement between PMEs interconnected by point-to-point links shownin the lower right corner.

2. This is our minimal-ist approach to processor design permitting eightreplications of the PME per chip with the CMOS DRAM technology.

3. This processor portion of the PME provides about the minimum dataflowwidth required to encode a fast Instruction Set Architecture (ISA)--seeTables--which is required to permit effective MIMD or SIMD operation ofour MMP.

PME Resident Software

The PME is the smallest element of the APAP capable of executing astored program it can execute a program which is resident in someexternal control element and fed to it by the broadcast and controlinterface (BCI) in SIMD mode or it can execute a program which isresident in its own main memory (MIMD mode). It can dynamically switchbetween SIMD mode and MIMD mode representing SIMD/MIMD mode dualityfunctions, and also the system can execute these dualities at the sametime (SIMIMD mode). A particular PME can make this dynamic switch bymerely setting or resetting a bit in a control register. Since SIMD PMEsoftware is actually resident in the external control element, furtherdiscussion of this may be found in our discussion of the Array Directorand in related applications.

MIMD software is stored into the PME main memory while the PME is inSIMD mode. This is feasible since many of the PMEs will containidentical programs because they will be processing similar data in anasynchronous manner. Here we would note that these programs are notfixed, but they can be modified by loading the MIMD program from anexternal source during processing of other operations.

Since the PME instruction set architecture represented in the Tables isthat of a microcomputer, there are few restrictions with thisarchitecture on the functions which the PME can execute. Essentiallyeach PME can function like a RISC microprocessor. Typical MIMD PMEsoftware routines are listed below:

1. Basic control programs for dispatching and prioritizing the variousresident routines.

2. Communication software to pass data and control messages among thePMEs. This software would determine when a particular PME would gointo/out of the "circuit switched" mode. It performs a "store andforward" function as appropriate. It also initiates, sends, receives,and terminates messages between its own main memory and that of anotherPME.

3. Interrupt handling software completes the context switch, andresponds to an event which has caused the interrupt. These can includefail-safe routines and rerouting or reassignment of PMEs to an array.

4. Routines which implement the extended Instruction Set Architecturewhich we describe below. These routings perform macro level instructionssuch as extended precision fixed point arithmetic, floating pointarithmetic, vector arithmetic, and the like. This permits not onlycomplex math to be handled but image processing activities for displayof image data in multiple dimensions (2d and 3d images) and multimediaprocesses.

4. Standard mathematical library functions can be included. These canpreferably include LINPAK and VPSS routines. Since each PME may beoperating on a different element of a vector or matrix, the various PMEsmay all be executing different routines or differing portions of thesame matrix at one time.

5. Specialized routines for performing scatter/gather or sortingfunctions which take advantage of the APAP nodal interconnectionstructure and permit dynamic multi-dimensional routing are provided. Theroutines effectively take advantage of some amount of synchronizationprovided among the various PMEs, while permitting asynchronousoperations to continue. For sorts, there are sort routines. The APAP iswell suited to a Batcher Sort. Because that sort requires extensivecalculations to determine particular element to compare versus veryshort comparison cycles. Program synchronization is managed by the I/Ostatements. The program allows multiple data elements per PME and verylarge parallel sorts in quite a straight forward manner.

While each PME has its own resident software, the systems made fromthese microcomputers can execute higher level language processesdesigned for scalar and parallel machines. Thus the system can executeapplication programs which have been written for UNIX machines, or thoseof other operating systems, in high level languages such as Fortran, C,C++, FortranD, and so on.

It may be an interesting footnote that our processor concepts use anapproach to processor design which is quite old. Perhaps thirty years ofuse of a similar ISA design has occurred in IBM's military processors.We have been the first to recognize that this kind of design can be usedto advantage to leapfrog the dead ended current modern microprocessordesign when combined with our total PME design to move the technology toa new path for use in the next century.

Although the processor's design characteristics are quite different fromother modern microprocessors, similar gate constrained military andaerospace processors have used the design since the '60s. It providessufficient instructions and registers for straight forward compilerdevelopment, and both general and signal processing applications areeffectively running on this design. Our design has minimal gaterequirements, and IBM has implemented some similar concepts for yearswhen embedded chip designs were needed general purpose processing. Ouradoption now of parts of the older ISA design permits use of manyutilities and other software vehicles which will enable adoption of oursystems at a rapid rate because of the existing base and the knowledgethat many programmers have of the design concepts.

PME I/O

The PME will interface to the broadcast and control interface (BCI) busby either reading data from the bus into the ALU via the path labeledBCI in FIG. 8 or by fetching instructions from the bus directly into thedecode logic (not shown). The PME powers up in SIMD mode and in thatmode reads, decodes and executes instructions until encountering abranch. A broadcast command SIMD mode causes the transition to MIMD withinstructions fetched locally. A broadcast PME instruction `INTERNALDIOW` reverts the state.

PME I/O can be sending data, passing data or receiving data. Whensending data, the PME sets the CTL register to connect XMIT to either L,R, V, or X. H/W services then pass a block of data from memory to thetarget via the ALU multiplexer and the XMIT register. This processinginterleaves with normal instruction operation. Depending uponapplication requirements, the block of data transmitted can contain rawdata for a predefined PME and/or commands to establish paths. A PME thatreceives data will store input to memory and interrupt the active lowerlevel processing. The interpretation task at the interrupt level can usethe interrupt event to do task synchronization or initiate a transparentI/O operation (when data is addressed elsewhere.) During the transparentI/O operation, the PME is free to continue execution. Its CTL registermakes it a bridge. Data will pass through it without gating, and it willremain in that mode until an instruction or the data stream resets CTL.While a PME is passing data it cannot be a data source, but it can be adata sink for another message.

PME Broadcast Section

This is a chip-to-common control device interface. It can be used by thedevice that serves as a controller to command I/O, or test and diagnosethe complete chip.

Input is word sequences (either instruction or data) that are availableto subsets of PMEs. Associated with each word is a code indicating whichPMEs will use the word. The the BCI will use the word both to limit aPME's access to the interface and to assure that all required PMEsreceive data. This serves to adjust the BCI to the asynchronous PMEoperations. (Even when in SIMD mode PMEs are asynchronous due to I/O andinterrupt processing.) The mechanism permits PMEs to be formed intogroups which are controlled by interleaved sets of command/data wordsreceived over the BCI.

Besides delivering data to the PMEs, the BCI accepts request codes fromthe PME combines them, and transmits the integrated request. Thismechanism can be used in several ways. MIMD processes can be initiatedin a group of processors that all end with an output signal. The `AND`of signals triggers the controller to initiate a new process.Applications, in many cases, will not be able to load all required S/Win PME memory. Encoded request to the controller will be used to acquirea S/W overlay from perhaps the host's storage system.

The controller uses a serial scan loop through many chips to acquireinformation on individual chips or PMEs. These loops initially interfaceto the BCI but can in the BCI be bridged to individual PMEs.

Broadcast and Control Interface

The BCI broadcast and control interface provided on each chip provides aparallel input interface such that data or instructions can be sent tothe node. Incoming data is tagged with a subset identifier and the BCIincludes the functions required to assure that all PMEs within the node,operating within the subset, are provided the data or instructions. Theparallel interface of the BCI serves both as a port to permit data to bebroadcast to all PMEs and as the instruction interface during SIMDoperations. Satisfying both requirements plus extending thoserequirements to supporting subset operations is completely unique tothis design approach.

Our BCI parallel input interface permits data or instructions to be sentfrom a control element that is external to the node. The BCI contains"group assignment" registers (see the grouping concepts in our aboveapplication entitled GROUPING OF SIMD PICKETS) which are associated witheach of the PMEs. Incoming data words are tagged with a group identifierand the BCI includes the functions required to assure that all PMEswithin the node which are assigned to the dedicated group are providedthe data or instructions. The parallel interface of the BCI serves asboth a port to permit data to be broadcast to the PMEs during MIMDoperations, and as the PME instruction/immediate operand interfaceduring SIMD operations.

The BCI also provides two serial interfaces. The high speed serial portwill provide each PME with the capability to output a limited amount ofstatus information. That data is intended to:

1. signal our Array Director 610 when the PME, e.g. 500, has data thatneeds to be read or that the PME has completed some operation. It passesa message to the external control element represented by the ArrayDirector.

2. provide activity status such that external test and monitor elementscan illustrate the status of the entire system.

The standard serial port permits the external control element means forselectively accessing a specific PME for monitor and control purposes.Data passed over this interface can direct data from the BCI parallelinterface to a particular PME register or can select data from aparticular PME register and route it to the high speed serial port.These control points allow the external control element to monitor andcontrol individual PMEs during initial power up and diagnostic phases.It permits Array Director to input control data so as to direct the portto particular PME and node internal registers and access points. Theseregisters provide paths such that PME of a node can output data to theArray Director, and these registers permit the Array Director to inputdata to the units during initial power up and diagnostic phases. Datainput to access point can be used to control test and diagnosticoperations, ie. perform single instruction step, stop on compare, breakpoints, etc.

Node Topology

Our modified hypercube topology connection is most useful for massivelyparallel systems, while other less powerful connections can be used withour basic PMEs. Within our initial embodiment of the VLSI chip are eightPMEs with fully distributed PME internal hardware connections. Theinternal PME to PME chip configuration is a two rings of four PMEs, witheach PME also having one connection to a PME in the other ring. For thecase of eight PMEs in a VLSI chip this is a three dimensional binaryhypercube, however our approach in general does not use hypercubeorganizations within the chip. Each PME also provides for the escape ofone bus. In the initial embodiment the escaped buses form one ring arecalled +X, +Y, +W and +Z, while those from the other ring are labeledsimilarly except - (minus).

The specific chip organization is referred to as the node of the array,and a node can be in a cluster of the array. The nodes are connectedusing +-X and +-Y into an array, to create a cluster. The dimensionalityof the array is arbitrary, and in general greater than two which is thecondition required for developing a binary hypercube. The clusters arethen connected using +-W, +-Z into a array of clusters. Again, thedimensionality of the array is arbitrary. The result is the4-dimensional hypercube of nodes. The extension to a 5-dimensionalhypercube requires the usage of a 10 PME node and uses the additionaltwo buses, say +-E1 to connect the 4-dimensional hypercube into a vectorof hypercubes. We have then shown the pattern of extension to either oddor even radix hypercubes. This modified topology limits the cluster tocluster wiring while supporting the advantages of the hypercubeconnection.

Our wireability and topology configuration for massively parallelmachines has advantages in keeping the X and Y dimensions within ourcluster level of packaging, and in distributing the W and Z busconnections to all the neighboring clusters. After implementing thetechniques described, the product will be wireable, and manufacturablewhile maintaining the inherent characteristics of the topology defined.

The node consists of k * n PMEs plus the Broadcast and Control Interface(BCI) section. Here "n" represents the number of dimensions or rings,which characterize the modified hypercube, while "k" represents thenumber of rings that characterize the node. Although a node can containk rings it is a characteristic of the concept that only two of thoserings may provide escape buses. "n" and "k" is limited in our preferredembodiment, because of the physical chip package to N=4 and k=2. Thislimitation is a physical one, and different chips sets will allow otherand increased dimensionality in the array. In addition to being a partof the physical chip package, it is our preferred embodiment to providea grouping of PMEs that interconnect a set of rings in a modifiedhypercube. Each node will have 8 PMEs with their PME architecture andability to perform processing and data router functions. As such, n isthe dimensionality of the modified hypercube (see following section),i.e., a 4d modified hypercube's node element would be 8 PMEs while a 5dmodified hypercube's node would be 10 PMEs. For visualization of nodeswhich we can employ, refer to FIG. 6, as well as FIGS. 9 and 10 forvisualization of interconnections and see FIG. 11 for a block diagram ofeach node. FIGS. 15 and 16 elaborate on possible interconnections for anAPAP.

It will be noted that the application entitled "METHOD FORINTERCONNECTING AND SYSTEM OF INTERCONNECTED PROCESSING ELEMENTS" ofco-inventor David B. Rolfe, filed in the United States Patent andTrademark office on May 13, 1991, under U.S. Ser. No. 07/698,866,described the modified hypercube criteria which can preferably be usedin connection with our APAP MMP. That application is incorporated byreference and describes a method of interconnecting processing elementsin such a way that the number of connections per element can be balancedagainst the network diameter (worst case path length). This is done bycreating a topology that maintains many of the well known and desirabletopological properties of hypercubes while improving its flexibility byenumerating the nodes of the network in number systems whose base can bevaried. When using a base 2 number system this method creates thehypercube topology. The invention has fewer interconnections than ahypercube, uniform connections and preserves the properties of ahypercube. These properties include: 1) large number of alternate paths,2) very high aggregate bandwidth, and 3) well understood and existingmethods that can be used to map other common problem topologies with thetopology of the network. The result is a generalized non-binaryhypercube with less density. It will be understood that with thepreference we have given to the modified hypercube approach, in someapplications a conventional hypercube can be utilized. In connectingnodes, other approaches to a topology could be used; however, the oneswe describe herein are believed to be new and an advance, and we preferthe ones we describe.

The interconnection methods for the modified hypercube topology forinterconnecting a plurality of nodes in a network of PMEs:

1. defines a sets of integers e1, e2, e3, . . . such the product of allelements equals the number of PMEs in the network called M, while theproduct of all elements in the set excepting e1 and e2 is the number ofnodes called N, and the number of elements in the set called m definesthe dimensionality of the network n by the relationship n=m-2.

2. addresses a PME located by a set of indexes a1, a2, . . . am, whereeach index is the PMEs position in the equivalent level of expansionsuch that the index ai is in the range of zero to ei-1 for i equal to 1,2, to m., by the formula (. . . (a(m) * e(m-1)+a (m-2))e(m-1) . . .a(2)*e(1))+a(1) where the notation a(i) has the normal meaning of thethe ith element in the list of elements called a, or equivalently for e.

3. connects two PMEs (with addresses f and g) if and only if either ofthe following two conditions hold:

a. the integer part of r/(e1 * e2) equals the integer part of s/(e1 *e2) and:

1) the remainder part of r/e1 differs from the remainder part of s/e1 by1 or,

2) the remainder part of r/e2 differs from the remainder part of s/e2 by1 or e2-1.

b. the remainder part of r/ei differs from the remainder part of s/eifor i in the range 3, 4, . . . m and the remainder part of r/e1 equalsthe remainder part of s/e2 which equals i minus three, and the remainderpart of r/e2 differs from the remainder part of s/e2 by e2 minus one.

As a result the computing system nodes will form a non-binary hypercube,with the potential for being different radix in each dimension. The nodeis defined as an array of PMEs which supports 2*n ports such that theports provided by nodes match the dimensionality requirements of themodified hypercube. If the set of integers e3, e4, . . . em, whichdefine the specific extent of each dimension of a particular modifiedhypercube are all taken as equal, say b, and if e1 and e2 are taken a 1,then the previous formulas for addressability and connections reduce to:

1. N=b * * n

2. addressing a PME as numbers representing the base b numbering system

3. connecting two computing elements (f and g) if and only if theaddress of f differs from the address of g in exactly one base b digit.using the rule that 0 and b-1 are separated by 1.

4. the number of connections supported by each PME is 2*n

Which is exactly as described in the base application, with the numberof communication buses spanning non-adjacent PMEs chosen as zero.

Intra-Node PME Interconnections

PMEs are configured within the node as a 2 by n array. Each PME isinterconnected with its three neighbors (edges wrap only in the seconddimension) using a set of input/output ports, thus, providing fullduplex communication capability between PMEs. Each PMEs external inputand output port is connected to node I/O pins. Input and output portsmay be connected to share pins for half-duplex communication or toseparate pins for full-duplex capability. The interconnections for a 4dmodified hypercube node are shown in FIGS. 9 and 10. (Note that where nis even the node can be considered to be a 2 by 2 by n/2 array.)

FIG. 9 illustrates the the eight processing elements 500, 510, 520, 530,540, 550, 560, 570 within the node. The PMEs are connected in a binaryhypercube communication network. This binary hypercube displays threeintra connections between PMEs (501, 511 521, 531, 541, 551, 561, 571,590, 591, 592, 593). Communication between the PME is controlled by inand out registers under control of the processing element. This diagramshows the various paths that can be taken to escape I/O out any of theeight directions, +-w 525, 565, +-x 515, 555, +-y 505, 545, +-z 535,575. The communication can be accomplished without storing the data intomemory if desired.

It may be noted that while a network switch chip could be employed toconnect various cards each having our chip with other chips of thesystem, it can and should desirably be eliminated. Our inter PME networkthat we describe as the "4d torus" is the mechanism used for interPME-communication. A PME can reach any other PME in the array on thisinterface. (PMEs in between may be Store/Forward or Circuit Switched)

Chip Relationships for Interconnections

We have discussed the chip, and FIG. 11 shows a block diagram of the PMEProcessor/Memory chip. The chip consists of the following elements eachof which will be described in later paragraphs:

1. 8 PMEs each consisting of a 16 bit programmable processor and 32Kwords of memory (64K bytes),

2. Broadcast Interface (BCI) to permit a controller to operate all orsubsets of the PMEs and to accumulate PME requests,

3. Interconnection Levels

a. Each PME supports four 8 bit wide inter-PME communication paths.These connect to 3 neighboring PMEs on the chip and 1 off chip PME.

b. Broadcast-to-PME busing, which makes data or instructions available.

c. Service Request lines that permit any PME to send a code to thecontroller. The BCI combines the requests and forwards a summary.

d. Serial Service loops permit the controller to read all detail aboutthe functional blocks. This level of interconnection extends from theBCI to all PMEs (FIG. 11 for ease of presentation omits this detail.)

Interconnection and Routing

The MPP will be implemented by replication of the PME. The degree ofreplication does not affect the interconnection and routing schemesused. FIG. 6 provides an overview of the network interconnection scheme.The chip contains 8 PMEs with interconnections to their immediateneighbors. This interconnection pattern results in the three dimensionalcube structure shown in FIG. 10. Each of the processors within the cubehas a dedicated bidirectional byte port to the chip's pins; we refer tothe set of 8 PMEs as a node.

An n by n array of nodes is a cluster. Simple bridging between the + and-x ports and the + and -y ports provide the cluster nodeinterconnections. Here the our preferred chip or node has 8 PMEs, eachof which manages a single external port. This distributes the networkcontrol function and eliminates a possible bottleneck for ports.Bridging the outer edges makes the cluster into a logical torus. We haveconsidered clusters with n=4 and n=8 and believe that n=8 is the bettersolution for commercial applications while n=4 is better for militaryconduction cooled applications. Our concept does not impose anunchangeable cluster size. On the contrary, we anticipate someapplications using variations.

An array of clusters results in the 4 dimensional torus or hypercubestructure illustrated in FIG. 10. Bridging between the + and -w portsand + and -z ports provides the 4d torus interconnections. This resultsin each node within a cluster connected to an equivalent node in alladjacent clusters. (This provides 64 ports between two adjacent clustersrather than the 8 ports that would result from larger clusters.) As withthe cluster size, the scheme does not imply a particular size array. Wehave considered 2×1 arrays desirable for workstations and MILapplications and 4×4, 4×8 and 8×8 arrays for mainframe applications.

Developing an array of 4d toruses is beyond the gate, pin, and connectorlimitations of our current preferred chip. However, that limitationdisappears with our alternative on-chip optical driver/receiver isemployed. In this embodiment our network could use an optical path perPME; with 12 rather than 8 PMEs per chip the array of 4d toruses withmulti-Tflop (Teraflop) performance and it seems to be economicallyfeasible to make such machines available for the workstationenvironment. Remember that such alternative machines will use theapplication programs developed for our current preferred embodiment.

4d Cluster Organization

For constructing a 4d modified hypercube 360, as illustrated in FIGS. 6and 10, nodes supporting 8 external ports 315 are required. Consider theexternal ports to be labeled as +X, +Y, +Z, +W, -X, -Y, -Z, -W. Thenusing m₁ nodes, a ring can be constructed by connecting the +X to -Xports. Again m₂ such rings can be interconnected into a ring of rings byinterconnecting the matching +Y to -Y ports. This level of structurewill be called a cluster 320. With m₁ =m₂ =8 it provides for 512 PMEsand such a cluster will be a building block for several size systems(330, 340, 350), as illustrated with m=8 in FIG. 6.

4d Array Organization

For building large fine-grained systems, sets of m₃ clusters areinterconnected in rows using the +Z to -Z ports. The m₄ rows are theninterconnected using the +W to -W ports. For m₁ = . . . m₄ =8 thisresults in system with 32768 or 8⁴⁺¹ PMEs. The organization does notrequire that every dimension be equally populated as shown in FIG. 6(large fine-grained parallel processor 370). In the case of thefine-grained small processor, only a cluster might be used with theunused Z and W ports being interconnected on the card. This techniquesaves card connector pins and makes possible the application of thisscalable processor to workstations 340, 350 and avionics applications330, both of which are connector pin limited. Connecting +/- portstogether in the Z and W pairs leads to a workstation organization thatpermits debug, test and large machine software development.

Again, much smaller scale versions of the structure can be developed bygenerating the structure with a value smaller than m=8. This will permitconstruction of single card processors compatible with the requirementsfor accelerators in the PS/2 or RISC System 6000 workstation 350.

I/O Performance

I/O performance includes overhead to setup transfers and actual burstrate data movement. Setup overhead depends upon application function I/Ocomplexity and network contention. For example, an application canprogram circuit switched traffic with buffering to resolve conflicts orit can have all PMEs transmit left and synchronize. In the first case,I/O is a major task and detailed analysis would be used to size it. Weestimate that simple case setup overhead is 20 to 30 clock cycles or 0.8to 1.2 u-sec.

Burst rate I/O is the maximum rate a PME can transfer data (with eitheran on or off chip neighbor.) Memory access limits set the data rate at140 nsec per byte, corresponding to 7.14 Mbyte/s. This performanceincludes buffer address and count processing plus data read/write. Ituses seven 40 ns cycles per 16 bit word transferred.

This burst rate performance corresponds to a cluster having a maximumpotential transfer rate of 3.65 Gbytes/s. It also means that a set ofeight nodes along a row or column of the cluster will achieve 57 Mbyte/sburst data rate using one set of their 8 available ports. This number issignificant because I/O with the external world will be done bylogically `unzipping` an edge of the wrapped cluster and attaching it tothe external system bus.

Inter-PME Routing Protocol

The SIMD/MIMD PME comprises interprocessor communication to the externalI/O facilities, broadcast control interfaces, and switching featureswhich allow both SIMD/MIMD operation within the same PME. Embedded inthe PME is the fully distributed programmable I/O router for processorcommunication and data transfers between PMEs.

The PMEs have fully distributed interprocessor communication hardware toon-chip PMEs as well as to the external I/O facilities which connect tothe interconnected PMEs in the modified hypercube configuration. Thishardware is complemented with the flexible programmability of the PME tocontrol the I/O activity via software. The programmable I/O routerfunctions provide for generating data packets and packet addresses. Withthis information the PME can send the information thru the network ofPMEs in a directed method or out multiple paths determined by any faulttolerance requirements.

Distributed fault tolerance algorithms or program algorithms can takeadvantage of the programmability along with the supported circuitswitched modes of the PME. This performance combinational mode enableseverything from off-line PMEs or optimal path data structures to beaccomplished via the programmable I/O router.

Our study of applications reveals that it is sometimes most efficient tosend bare data between PMEs. At other times applications require dataand routing information. Further, it is sometimes possible to plancommunications so that network conflicts cannot occur; otherapplications offer the potential for deadlock, unless mechanisms forbuffering messages at intermediate nodes are provided. Two examplesillustrate the extremes. In the relaxation phase of a PDE solution, eachgrid point can be allocated to a node. The inner loop process ofacquiring data from a neighbor can easily be synchronized over allnodes. Alternatively, image transformations use local data parameters todetermine communication target or source identifiers. This results indata moves through multiple PMEs, and each PME becomes involved in therouting task for each packet. Preplanning such traffic is generally notpossible.

To enable the network to be efficient for all types of transferrequirements, we partition, between the H/W and S/W, the responsibilityfor data routing between PMEs. S/W does most of the task sequencingfunction. We added special features to the hardware (H/W) to do theinner loop transfers and minimize software (S/W) overhead on the outerloops.

I/O programs at dedicated interrupt levels manage the network. For mostapplications, a PME dedicates four interrupt levels to receiving datafrom the four neighbors. We open a buffer at each level by loadingregisters at the level, and executing the IN (it uses buffer address andtransfer count but does not await data receipt) and RETURN instructionpair. Hardware then accepts words from the particular input bus andstores them to the buffer. The buffer full condition will then generatethe interrupt and restore the program counter to the instruction afterthe RETURN. This approach to interrupt levels permits I/O programs to bewritten that do not need to test what caused the interrupt. Programsread data, return, and then continue directly into processing the datathey read. Transfer overhead is minimized as most situations requirelittle or no register saving. Where an application uses synchronizationon I/O, as in the PDE example, then programs can be used to provide thatcapability.

Write operations can be started in several ways. For the PDE example, atthe point where a result is to be sent to a neighbor, the applicationlevel program executes a write call. The call provides buffer location,word count and target address. The write subroutine includes theregister loads and OUT instructions needed to initiate the H/W andreturn to the application. H/W does the actual byte by byte datatransfer. More complicated output requirements will use an outputservice function at the highest interrupt level. Both application andinterrupt level tasks access that service via a soft interrupt.

Setting up circuit switched paths builds on these simple read and writeoperations. We start with all PMEs having open buffers sized to acceptpacket headers but not the data. A PME needing to send data initiatesthe transfer by sending an address/data block to a neighboring PME whoseaddress better matches the target. In the neighboring PME addressinformation will be stored; due to buffer full an interrupt will occur.The interrupt S/W tests the target address and will either extend thebuffer to accept the data or write the target address to an output portand set the CTL register for transparent data movement. (This allows thePME to overlap its application executions with the circuit switchedbridging operation.) The CTL register goes to busy state and remainstransparent until reset by the presence of a signal at end of datastream or abnormally by PME programming. Any number of variations onthese themes can be implemented.

System I/O and Array Director

FIG. 12 shows an Array Director in the preferred embodiment, which mayperform the functions of the controller of FIG. 13 which describes thesystem bus to array connections. FIG. 13 is composed of two parts, (a)the bus to/from a cluster, and part (b) the communication of informationon the bus to/from a PME. Loading or unloading the array is done byconnecting the edges of clusters to the system bus. Multiple systembuses can be supported with multiple clusters. Each cluster supports 50to 57 Mbyte/s bandwidth. Loading or unloading the parallel arrayrequires moving data between all or a subset of the PMEs and standardbuses (ie MicroChannel, VME-bus, FutureBus, etc). Those buses, part ofthe host processor or array controller, are assumed to be rigidlyspecified. The PME Array therefore must be adapted to the buses. The PMEArray can be matched to the bandwidth of any bus by interleaving busdata onto n PMEs, with n picked to permit PMEs both I/O and processingtime. FIG. 13 shows how we might connect the system buses to the PMEs attwo edges of a cluster. Such an approach would permit 114 Mbyte/s to besupported. It also permits data to be loaded at half the peak rate totwo edges simultaneously. Although this reduces the bandwidth to 57Mbyte/s/cluster, it has the advantage of providing orthogonal datamovement within the array and ability to pass data between two buses.(We use those advantages to provide fast transpose and matrix multiplyoperation.)

As shown in part (a) of FIG. 13, the bus dots to all paths on the edgesof the cluster; and, the controller generates a gate signal to each pathin the required interleave timing. If required to connect to a systembus with greater than 57 Mbyte/s, the data will be interleaved overmultiple clusters. For example, in a system requiring 200 Mbyte/s systembuses, groups of 2 or 4 clusters will be used. A large MPP has thecapacity to attach 16 or 64 such buses to its xy network paths. By usingthe w and z paths in addition to the x and y paths, that number could bedoubled.

FIG. 13 part (b) shows how the data routes to individual PMEs. TheFIGURE shows one particular w,x,y or z path that can be operated at 7.13Mbyte/s in burst mode. If the data on the system bus occurred in bursts,and if the PME memory could contain the complete burst, then only onePME would be required. We designed the PME I/O structure to requireneither of these conditions. Data can be gated into the PME×0 at thefull rate until buffer full occurs. At that instant, PME×0 will changeto transparent and PME×1 will begin accepting the data. Within PME×0processing of the input data buffer can begin. PMEs that have taken dataand processed it are limited because they cannot transmit the resultswhile in the transparent mode. The design resolves this by switching thedata stream to the opposite end of the path at intervals. FIG. 13(b)shows that under S/W control one might dedicate PME×0 through PME×3 toaccepting data while PME×12 through PME×15 unload results andvisa-versa. The controller counts words and adds end of block signals tothe data stream, causing the switch in direction. One count applies toall paths supported by the controller so controller workload isreasonable.

SYSTEMS FOR ALTERNATIVE COMPUTERS

FIG. 18 illustrates a system block diagram for a host attached largesystem with a single application processor interface (API). Thisillustration may also be viewed with the understanding that ourinvention may be employed in stand alone system which use multipleapplication processor interfaces (not shown) This configuration willsupport DASD/Grahpics on all or many clusters. Workstation acceleratorscan eliminate the host, application processor interface (API) andcluster synchronizer (CS) illustrated by emulation. The CS not alwaysrequired. It will depend on the type of processing that is beingperformed, as well as the physical drive or power provided for aparticular application which uses our invention. An application this isdoing mostly MIMD processing will not place as high a workload demand onthe controller, so here the control bus can see very slow pulse risetimes. Conversely, system doing mostly asynchronous A-SIMD operationswith many independent groupings may require faster control busing. Inthis case, a cluster synchronizer will be desirable.

The system block diagram of FIG. 18 illustrates that a system mightconsist of host, array controller and PME array. The PME array is a setof clusters supported by a set of cluster controllers (CC). Although aCC is shown for each cluster that relationship is not strictly required.The actual ratio of clusters to CCs is flexible. The CC provides redriveto, and accumulation from the 64 BCIs/clusters. Therefore, physicalparameters can be used establish the maximum ratio. Additionally, the CCwill provide for controlling multiple independent subsets of the PMEarray; that service might also become a gating requirement. A study canbe made to determine these requirements for any particular applicationof our invention. Two versions of the CC will be used. A cluster that isto be connected to a system bus requires the CC providing interleavecontrols (see System I/O and FIG. 18) and tri-state drivers. A moresimple version that omits the tri-state busing features can also beemployed. In the case of large systems, a second stage of redrive andaccumulation is added. This level is the cluster synchronizer (CS). Theset of CCs plus CS and the Application Processor Interface (API) make upthe Array Controller. Only the API is a programmable unit.

Several variations of this system synthesis scheme will be used. Theseresult in different hardware configurations for various applications,but they do not have a major impact on the supporting software.

For a workstation accelerator, the cluster controllers will be attacheddirectly to the workstation system bus; the function of the API will beperformed by the workstation. In the case of a RISC/6000, the system busis a Micro Channel and the CC units can plug directly into the slotswithin the workstation. This configuration places the I/O devices (DASD,SCSI and display interfaces) on the same bus that loads/unloads thearray. As such the parallel array can be used for I/O intensive taskslike real time image generation or processing. For workstations usingother bus systems (VME-bus, FutureBus, etc.), a gateway interface willbe used. Such modules are readily available in the commercialmarketplace. Note that in these minimal scale systems a single CC can beshared between a determined number of clusters, and neither a CS nor anAPI is needed.

A MIL avionics application might be similar in size to a workstation,but it needs different interfacing. Consider what may become the normalmilitary situation. An existing platform must be enhanced withadditional processing capability, but funding prohibits a completeprocessing system redesign. For this we would attach to the APAP array asmart memory coprocessor. In this case, a special application programinterface API that appears to the host as memory will be provided. Dataaddressed to the host's memory will then be moved to the array viaCC(s). Subsequent writes to memory can be detected and interpreted ascommands by the API so that the accelerator appears to be a memorymapped coprocessor.

Large systems can be developed as either host attached or as stand aloneconfigurations. For a host attached system, the configuration shown inFIG. 18 is useful. The host will be responsible for I/O, and the APIwould serve as a dispatched task manager. However, a large stand alonesystem is also possible in special situations. For example, a databasesearch system might eliminate the host, attach DASD to the MicroChannelsof every cluster and use multiple APIs as bus masters slaved to thePMEs.

Zipper Array Interface with External I/O

Our zipper provides a fast I/O connection scheme and is accomplished byplacing a switch between two nodes of the array. This switch will allowfor the parallel communication into and out of the array. The fast I/Owill be implemented along one edge of the array rings and acts like alarge zipper into the X, Y, W, Z rings. The name "zipper connection" isgiven to the fast I/O. Allowing data to be transferred into and out ofthe network while only adding switch delays to transfer the data betweenprocessors is a unique loading technique. The switching scheme does notdisrupt the ring topology created by the X, Y, W, Z buses and specialsupport hardware allows the zipper operation to occur while the PE isprocessing or routing data.

The ability to bring data into and out of a massively parallel systemrapidly is an important enhancement to the performance of the overallsystem. We believe that the way we implement our fast I/O withoutreducing the number of processors or dimension of the array network isunique in the field of massively parallel environments.

The modified hypercube arrangement can be extended to permit a topologywhich comprises rings within rings. To support the interface to theexternal I/O any or all of the rings can be logically broken. The twoends of the broken ring can then be connected to external I/O buses.Breaking the rings is a logical operation so as to permit regularinter-PME communication at certain time intervals while permitting I/Oat other time intervals. This process of breaking a level of ringswithin the modified hypercube effectively `unzips` rings for I/Opurposes. The fast I/O "zipper" provides a separate interface into thearray. This zipper may exist on 1 to n edges of the modified hypercubeand could support either parallel input into multiple dimensions of thearray or broadcast to multiple dimensions of the array. Further datatransfers into or out of the array could alternate between the two nodesdirectly attached to the zipper. This I/O approach is unique and itpermits developing different zipper sizes to satisfy particularapplication requirements. For example, in the particular configurationshown in FIG. 6, called the large fine-grained processor 360, the zipperfor the Z and W buses will be dotted onto the MCA bus. This approachoptimizes the matrix transposition time, satisfying a particularapplication requirement for the processor. For a more detailedexplanation of the "zipper" structure, reference may be had to the APAPI/O ZIPPER application filed filed concurrently herewith. The zipper ishere illustrated by FIG. 14.

Depending on the configuration and the need of the program to roll dataand program into and out of the individual processing elements, the sizeof the zipper can be varied. The actual speed of the I/O zipper isapproximately the number of rings attached times the PME bus width,times the PME clock rate all divided by 2. (The division permits thereceiving PME time to move data onward. Since it can send it to any of nplaces I/O contention is completely absorbed over the Array.) Withexisting technology, ie., 5 MB/sec PME transfer rate, 64 rings on thezipper, and interleaved to two nodes transfers, 320 MB/sec Arraytransfer rates are possible. (See the typical zipper configuration inFIG. 14). FIG. 14 illustrates the fast I/O or the so-called "zipperconnection" 700, 710 which exists as a separate interface into thearray. This zipper may exist on one 700 or two edges 700, 710 of thehypercube network by dotting onto the broadcast bus 720, 730, 740, 750,at multiple nodes in the array 751, 752, 753, 754 and in multipledirections 770, 780, 790, 751, 755, 757.

Today's MCA bus supports 80 to 160 MB per second burst transfer rate andtherefore is a good match for a single zipper in simple ornon-interleaved mode. The actual transfer rate given channel overheadand efficiency is something less than that. For systems that have evenmore demanding I/O requirements, multiple zippers and MCA buses can beutilized. These techniques are seen to be important to processors thatwould support a large external storage associated with nodes orclusters, as might be characteristic of database machines. Such I/Ogrowth capability is completely unique to this machine and has notpreviously been incorporated in either massively parallel, conventionalsingle processor, or coarse-grained parallel machines.

Array Director Architecture

Our massively parallel system is made up of nodal building blocks ofmultiprocessor nodes, clusters of nodes, and arrays of PMEs alreadypackaged in clusters. For control of these packaged systems we provide asystem array director which with the hardware controllers performs theoverall Processing Memory Element (PME) Array Controller functions inthe massively parallel processing environment. The Director comprises ofthree functional areas, the Application Interface, the ClusterSynchronizer, and normally a Cluster Controller. The Array Director willhave the overall control of the PME array, using the broadcast bus andour zipper connection to steer data and commands to all of the PMEs. TheArray Director functions as a software system interacting with thehardware to perform the role as the shell of the operating system. TheArray Director in performing this role receives commands from theapplication interface and issuing the appropriate array instructions andhardware sequences to accomplish the designated task. The ArrayDirector's main function is to continuously feed the instructions to thePMEs and route data in optimal sequences to keep the traffic at amaximum and collisions to a minimum.

The APAP computer system shown in FIG. 6 is illustrated in more detailin the diagram of FIG. 12 which illustrates the Array Director which canfunction as a controller, or array controller, as illustrated in FIG. 13and FIGS. 18 and 19. This Array Director 610 illustrated in FIG. 12 isshown in the preferred embodiment of an APAP in a typical configurationof n identical array clusters 665, 670, 680, 690, with an array director610 for the clusters of 512 PMEs, and an application processor interface630 for the application processor or processors 600. The synchronizer650 provides the needed sequences to the array or cluster controller 640and together they make up the "Array Director" 610. The applicationprocessor interface 630 will provide the support for the host processor600 or processors and test/debug workstations. For APAP units attachedto one or more hosts, the Array Director serves as the interface betweenthe user and the array of PMEs. For APAPs functioning as stand aloneparallel processing machines, the Array Director becomes the host unitand accordingly becomes involved in unit I/O activities.

The Array Director will consist of the following four functional areas:(see the functional block diagram in FIG. 12)

1. Application Processor Interface (API) 600,

2. Cluster Synchronizer (CS) 650 (8×8 array of clusters),

3. Cluster Controller (CC) 640 (8×1 array of nodes),

4. Fast I/O (zipper Connection) 620.

The Application Processor Interface (API) 630

When operating in attached modes, one API will be used for each host.That API will monitor the incoming data stream to determine what areinstructions to the Array clusters 665, 670, 680, 690 and what are datafor the Fast I/O (zipper) 620. When in standalone mode, the API servesas the primary user program host.

To support these various requirements, the APIs contain the onlyprocessors within the Array Director, plus the dedicated storage for theAPI program and commands. Instructions received from the host can callfor execution of API subroutines, loading of API memory with additionalfunctions, or for loading of CC and PME memory with new S/W. Asdescribed in the S/W overview section, these various type requests canbe restricted to subset of users via the initial programs loaded intothe API. Thus, the operating program loaded will determine the type ofsupport provided which can be tailored to match the performancecapability of the API. This further permits the APAP to be adjusted tothe needs of multiple users requiring managed and well tested services,or to the individual user wishing to obtain peak performance on aparticular application.

The API also provides for managing the path to and from the I/O zipper.Data received from the host system in attached modes, or from devices instandalone modes is forwarded to the Array. Prior to initiating thistype of operation the PMEs within the Array which will be managing theI/O are initiated. PMEs operating in MIMD mode can utilize the fastinterrupt capability and either standard S/W or special functions forthis transfer while those operating in SIMD modes would have to beprovided detailed control instructions. Data being sent from the I/Ozipper requires somewhat the opposite conditioning. PMEs operating inMIMD modes must signal the API via the high speed serial interface andawait a response from the API, while PMEs in SIMD modes are already insynchronization with the API and can therefore immediately output data.The ability to system switch between modes provides a unique ability toadjust the program to the application.

Cluster Synchronizer (CS) 650

The CS 650 provides the bridge between the API 630 and CC 640. It storesAPI 630 output in FIFO stacks and monitors the status being returnedfrom the CC 650 (both parallel input acknowledges and high speed serialbus data) to provide the CC, in timely fashion, with the desiredroutines or operations that need to be started. The CS provides thecapability to support different CCs and different PMEs within clustersso as to permit dividing the array into subsets. This is done bypartitioning the array and then commanding the involved clustercontrollers to selectively forward the desired operation. The primaryfunction of the synchronizer is to keep all clusters operating andorganized such that overhead time is minimized or buried under thecovers of PME execution time. We have described how the use of thecluster synchronizer in A-SIMD configurations is especially desirable.

Cluster Controller (CC) 640

The CC 640 interfaces to the node Broadcast and Control Interface (BCI)605 for the set of nodes in an array cluster 665. (For a 4d modifiedhypercube with 8 nodes per ring that means the CC 640 is attached to 64BCIs 605 in an 8 by 8 array of nodes and is controlling 512 PMEs.Sixty-four such clusters, also in a 8 by 8 array, lead to the full upsystem with 32768 PMEs.) The CC 640 will send commands and data suppliedby the CS 650 to the BCI parallel port and return the acknowledgementdata to the CS 650 when operating in MIMD modes. In SIMD mode theinterface operates synchronously, and step by step acknowledgments arenot required. The CC 640 also manages and monitors the high speed serialport to determine when PMEs within the nodes are requesting services.Such requests are passed upward to the CS 650 while the raw data fromthe high speed serial interface is made available to the status displayinterface. The CC 640 provides the CS 650 with an interface to specificnodes within the cluster via the standard speed serial interface.

In SIMD mode the CC will be directed to send instructions or addressesto all the PMEs over the broadcast bus. The CC can dispatch 16 bitinstruction to all PMEs every 40 nanoseconds when in SIMD mode. Bybroadcasting groups of native instructions to the PME, the emulatedinstruction set is formed.

When in MIMD mode the CC will wait for the endop signal before issuingnew instructions to the PMEs. The concept of the MIMD mode is to buildstrings of micro-routines with native instructions resident in the PME.These strings can be grouped together to form the emulated instructions,and these emulated instruction can be combined to produce service/cannedroutines or library functions.

When in SIMD/MIMD (SIMIMD) mode, the CC will issue instruction as if inSIMD mode and check for endop signals from certain PMEs. The PMEs thatare in MIMD will not respond to the broadcast instructions and willcontinue with there designated operation. The unique status indicatorswill help the CC to manage this operation and determine when and to whomto present the sequential instructions.

Operational Software Levels

This application overviews the operational software S/W levels toprovide further explanation of the services performed by varioushardware H/W components.

Computer systems generally used have an operating system. Operatingsystem kernels which are relatively complete must be provided in mostmassive MIMD machines, where workstation class CPU chips run kernelssuch as Mach. The operating system kernal supports message passing ormemory coherency. Other massively parallel systems based upon SIMDmodels have almost no intelligence in the array. There are no "programcounters" out in the array, and thus no programs to execute locally. Allinstructions are broadcast.

In the systems we have provided with our PME as the basis for clusterarrays, there is not need for an operating system at each chip, a node.We provide a library of key functions for computation and/orcommunication within each PE (PME) that can be invoked at a high level.SIMD-like instructions are broadcast to the array to set each of aselected set of PMEs. These PMEs can then perform in full MIMD mode oneor more of these library routines. In addtion, basic interupt handlerand communications routines are resident in each PME allowing the PME tohandle communication on a dynamic basis. Unlike existing MIMD machines,the APAP structure need not include an entire program in PME memory.Instead all of that code, which is essentially serial, is the clustercontroller. Thus such code, 90% by space and 10% by time (typically) canbe broadcast in a SIMD fashio to an array of PMEs. Only the trulyparallel inner loops are distributed to the PMEs in a dynamic fashion.These are then initiated into MIMD mode just as other "library" routinesare. This enables use of program models which are Single ProgramMultiple data to be used where the same program is loaded in each PMEnode, with embedded synchronization code, and executed at the local PME.Design parameters affect bandwidth available on different links, and thesystem paths are programmatically configurable, allowing high bandwithlinks on a target network, and allowing dynamic partition of off chiplike PME-to-PME links to provide more bandwidth on specific paths asmeets the needs of a particular application. The links leaving a chipmate directly with each other, without the need for external logic.There are sufficient links and there is no predesigned constraint as towhich other links they can attach to, so that the system can have adiversity of interconnection topologies, with routing performeddynamically and programmatically.

The system allows usage of existing compilers and parsers to create anexecutable parallel program which could run on a host or workstationbased configuration. Sequential source code for a Single ProgramMultiple Data system would pass through program analysis, forexamination of dependency, data and controls, enabling extension ofprogram source to include call graphs, dependency tables, aliases, usagetables and the like. Therafter, program transformation would occurwhereby a modified version of the program would be created that extendsthe degreee of parallelism by combining sequences or recognizingpatterns to generate explicit compiler directives. A next step would bea data allocation and partitioning step, with message generation, whichwould analyze data usage patternsnd allocate so that elements to becombined would share common indexing, addressing pattern, and thesewould provide embedded program compiler directives and calls tocommunication services. At this point the program would pass to a levelpartitioning step. A level partitioning step would separate the programinto portions for execution in ARRAY, in ARRAY CONTROLLER (arraydirector or cluster controller), and HOST. Array portions would beinterleaved in sections with any required message passingsynchronization functions. At this point, level processing couldproceed. Host sources would pass to a level compiler (FORTRAN) forassembly compilation. Controller sources would pass to a microprocessorcontroller compiler, and items that would be needed by a single PME andnot available in a library call would pass to a parser (FORTRAN OR C) toan intermediate level language representation which would generateoptimized PME code and Array Controller code. PME code would be createdat PME machine level, and would include library extensions, which wouldpass on load into a PME memory. During execution a PME parallel programin the SPMD process of execution could call upon already coded assemblyservice functions from a runtime library kernel.

Since the APAP can function as either an attached unit that is closelyor loosely coupled with its host or as a stand alone processor, somevariation in the upper level S/W models exists. However, thesevariations serve to integrate the various type applications so as topermit a single set of lower level functions to satisfy all threeapplications. The explanation will address the attached version S/Wfirst and then the modifications required for standalone modes.

In any system, as illustrated by FIG. 18, where the APAP is intended toattach to a host processor the user's primary program would exist withinthe host and would delegate to the APAP unit tasks and associated dataas needed to provide desired load balancing. The choice of interpretingthe dispatched task's program within the host or the Array Director is auser option. Host level interpretation permits the Array Director towork at interleaving users which do not exploit close control of theArray, while APAP interpretation leads to minimal latency in controlbranching but tends to limit the APAP time to perform multi-usermanagement tasks. This leads to the concept that the APAP and host canbe tightly or loosely coupled.

Two examples illustrate the extremes:

1. When APAP is attached to 3090 class machines with Floating PointVector Facilities, user data in compressed form could be stored withinthe APAP. A host program that called for a vector operation upon twovectors with differing sparseness characteristics would then sendinstructions to the APAP to realign the data into element by elementmatching pairs, output the result to the Vector Facility, read answerfrom the Vector Facility and finally reconfigure data into final sparsedata form. Segments of the APAP would be interpreting and buildingsparse matrix bit maps, while other sections would be calculating how tomove data between PMEs such that it would be properly aligned for thezipper.

2. With APAP attached to a small inflight military computer, the APAPcould be performing the entire workload associated with Sensor FusionProcessing. The host might initiate the process once, send sensor dataas it was received to the APAP and then wait for results. The ArrayDirector would then have to schedule and sequence the PME array throughperhaps dozens of processing steps required to perform the process.

The APAP will support three levels of user control:

1. Casual User. S/he works with supplied routines and library function.These routines are maintained at the host or API level and can be evokedby the user via subroutine calls within his program.

2. Customizer User. S/he can write special functions which operatewithin the API and which directly evoke routines supplied with the APIor services supplied with the CC or PME.

3. Development User. S/he generates programs for execution in the CC orPME, depending upon API services for program load and status feedback.

Satisfying these three user levels in either closely of loosely coupledsystems leads to the partitioning of H/W control tasks.

API Software Tasks

The application program interface API contains S/W services that cantest the leading words of data received and can determine whether thatdata should be interpreted by the API, loaded to some storage within theArray Director or PME, or passed to the I/O zipper.

For data that is to be interpreted, the API determines the requiredoperation and invokes the function. The most common type operation wouldcall for the Array to perform some function which would be executed as aresult of API writes to the CS (and indirectly to the CC). The actualdata written to the CS/CC would in general be constructed by the APIoperational routine based upon the parameters passed to the API from thehost. Data sent to the CS/CC would in turn be forwarded to the PMEs viathe node BCI.

Data could be loaded to either API storage, CC storage, or PME memory.Further, data to be loaded to PME memory could be loaded via either theI/O zipper or via the node BCI. For data to be put into the API memory,the incoming bus would be read then written to storage. Data targeted tothe CC memory would be similarly read and then be written to the CCmemory. Finally, data for the PME memory (in this case normally new oradditional MIMD programs) could be sent to all or selected PMEs via theCS/CC/Node BCI or to a subset of PMEs for selective redistribution viathe I/O zipper.

When data is to be sent to the I/O zipper, it could be preceded byinline commands that permit the PME MIMD programs to determine itsultimate target; or, it could be preceded by calls to the API servicefunctions to perform either MIMD initiation or SIMD transmission.

In addition to responding to requests for service received via the hostinterface, the API program will respond to request from the PMEs. Suchrequests will be generated on the high speed serial port and will berouted through the CC/CS combination. Requests of this sort can resultin the API program's directly servicing the PMEs or accessing the PMEsvia the standard speed serial port to determine further qualifying datarelative to the service request.

PME Software

The software plan includes:

Generation of PME resident service routines (that is, `an extended ISA`)for complex operations and I/O management.

Definition and development of controller executed subroutines thatproduce and pass control and parameter data to the PMEs via the BCI bus.These subroutines:

1. cause a set of PMEs to do mathematical operations on distributedobjects,

2. provide I/O data management and synchronization services for PMEArray and System Bus interactions,

3. provide startup program load, program overlay and program taskmanagement for PMEs.

Development of data allocation support services for host level programs,and

Development of a programming support system including assembler,simulator, and H/W monitor and debug workstation.

Based upon studies of military sensor fusion, optimization, imagetransformation, US Post Office optical character recognition and FBIfingerprint matching applications, we have concluded that a parallelprocessor programmed with vector and array commands (like BLAS calls)would be effective. The underlying programming model must match the PMEarray characteristics feasible with today's technology. Specifically:

PMEs can be independent stored program processors,

The array can have thousands of PMEs, and be suitable for fine grainedparallelism,

Inter-PME networks will have very high aggregate bandwidth and a small`logical diameter`,

But, by network connected microprocessor MIMD standards, each PME ismemory limited.

Prior programming on MIMD parallel processors has used task dispatchingmethodology. Such approaches lead to each PME needing access to anportion of a large program. This characteristic, in combination with thenon-shared memory characteristic of the H/W, would exhaust PME memory onany significant problem. We therefore target what we believe is a newprogramming model, called `asynchronous SIMD` (A-SIMD) type processing.In this connection see U.S. Ser. No. 798,788, filed Nov. 27, 1991 of P.Kogge, which is incorporated herein.

A-SIMD programming in our APAP design means that a group of PMEs will bedirected by commands broadcast to them as in SIMD models. The broadcastcommand will initiate execution of a MIMD function within each PME. Thatexecution can involve data dependent branching and addressing withinPMEs, and I/O based synchronization with either other PMEs or the BCI.Normally, PMEs will complete the processing and synchronize by readingthe next command from the BCI.

The A-SIMD approach includes both MIMD and SIMD operating modes. Sincethe approach imposes no actual time limits on the command executionperiod, a PME operation that synchronizes on data transfers and executesindefinitely can be initiated. Such functions are very effective in datafiltering, DSP, and systolic operations. (They can be ended by eitherBCI interrupts or by commands over the serial control buses.) SIMDoperation results from any A-SIMD control stream that does not includeMIMD Mode Commands. Such a control stream can include any of the PMEsnative instructions. These instructions are routed directly to theinstruction decode logic of the PME. Eliminating the PME instructionfetch provides a higher performance mode for tasks that do not involvedata dependent branching.

This programming model (supported by H/W features) extends to permittingthe array of PMEs to be divided into independent sections. A separateA-SIMD command stream controls each section. Our application studiesshow that programs of interest divide into separate phases (ie. input,input buffering, several processing steps, and output formatting, etc.),suitable for pipeline data processing. Fine-grained parallelism resultsfrom applying the n PMEs in a section to a program phase. Applyingcoarse-grained partitioning to applications often results in discoveringsmall repetitive tasks suitable for MIMD or memory bandwidth limitedtasks suitable for SIMD processing. We program the MIMD portions usingconventional techniques and program the remaining phases as A-SIMDsections, coded with vectorized commands, sequenced by the arraycontroller. This makes the large controller memory the program store.Varying the number of PMEs per section permits balancing the workload.Varying the dispatched task size permits balancing the BCI bus bandwidthto the control requirements.

The programming model also considers allocating data elements to PMEs.The approach is to distribute data elements evenly over PMEs. In earlyversions of S/W, this will be done by the programmer or by S/W. Werecognize that the IBM parallelizing compiler technologies apply to thisproblem and we expect to investigate their usage. However, the inter-PMEbandwidth provided does tend to reduce the importantly of this approach.This links data allocation and I/O mechanism performance.

The H/W requires that the PME initiate data transfers out of its memory,and it supports a controlled write into PME memory without PME programinvolvement. Input control occurs in the receiving PME by providing aninput buffer address and a maximum length. When I/O to a PME results inbuffer overflow, H/W will interrupt the receiving PME. The low level I/Ofunctions that will be developed for PMEs build on this service. We willsupport either movement of raw data between adjacent PMEs or movement ofaddressed data between any PMEs. The last capability depends upon thecircuit switched and store and forward mechanisms. The interpret addressand forward operation is important for performance. We have optimizedthe H/W and S/W to support the operation. Using one word buffers resultsin an interrupt upon receipt of address header. Comparing target id withlocal id permits output path selection. Transfer of the subsequent datawords occurs in circuit switched mode. A slight variation on thisprocess using larger buffers results in a store and forward mechanism.

Because of the high performance inter-PME bandwidth, it is not alwaysnecessary or desirable to place data elements within the PME Arraycarefully. Consider shifting a vector data element distributed acrossPMEs. Our architecture can send data without an address header, thus,providing for very fast I/O. However, we have found, in manyapplications, that optimizing a data structure for movement in onedirection, penalizes data movement in an orthogonal direction. Thepenalty in such situations approximates the average cost of randomlyrouting data in the network. This leads to applications where placingdata sequentially or randomly (as opposed to arranging data) results inshorter average process times.

Many applications can be synchronized to take advantage of averageaccess time. (For example, PDE relaxation processes acquire data from aneighborhood and thus, can average access over at least four I/Ooperations.) We believe that after considering the factors applicable tovector and array processes, like scatter/gather or row/columnarithmetic, many users will find brute force data allocation to besuitable for the application. However, we know of examples thatillustrate application characteristics (like required synchronization orbiased utilization of shift directions¹) that tend to force particulardata allocation patterns. This characteristic requires that the toolsand techniques developed support either manual tuning of the dataplacement, or simple and non-optimum data allocation. (We will supportthe non-optimum data allocation strategy with host level macros toprovide near transparent port of vectorized host programs to the MPP.The H/W Monitor workstation will permit the user to investigate theresultant performance.)

FIG. 19 shows the general S/W development and usage environment. TheHost Application Processor is optional in that program execution can becontrolled from either the Host or the Monitor. Further, the Monitorwill effectively replace the Array Controller is some situations. Theenvironment will support program execution on real or simulated MPPhardware. The Monitor is scenario driven so that the developer doingtest and debug operations can create procedures to permit effectiveoperation at any level of abstraction.

FIG. 20 illustrates the levels of H/W supported within the MPP and theuser interfaces to these levels.

We see two potential application programming techniques for the MPP. Inthe least programmer intensive approach, applications would be writtenin a vectorized high order language. If the user did not feel that theproblem warranted tuning data placement then he would use compile timeservices to allocate data to the PME Array. The application would usevector calls like BLAS that would be passed to the controller forinterpretation and execution on the PME Array. Unique calls would beused to move data between host and PME Array. In summary, the user wouldnot need to be aware of how the MPP organized or processed the data. Twooptimization techniques will be supported for this type application:

1. Altering the data allocation by constructing the data allocationtable will permit programs to force data placements.

2. Generation of additional vector commands for execution by the arraycontroller will permit tuned subfunctions (ie. calling the GaussianElimination as a single operation.)

We also see that the processor can be applied to specializedapplications as in those referenced in the beginning of this section. Insuch cases, code tuned to the application would be used. However, evenin such applications the degree of tuning will depend upon how importanta particular task is to the application. It is in this situation that wesee the need for tasks individually suited to SIMD, MIMD or A-SIMDmodes. These programs will use a combination of:

1. Sequences of PME native instructions passed to an emulator functionwithin the array controller. The emulator will broadcast the instructionand its' parameters to the PME set. The PMEs in this SIMD mode will passthe instruction to the decode function, simulating a memory fetchoperation.

2. Tight inner loops that can be I/O synchronized will use PME nativeISA programs. After initiation from a SIMD mode change, they would runcontinuously in MIMD mode. (The option to return to SIMD mode via a`RETURN` instruction exists.)

3. More complicated programs, as would be written in a vectorizingcommand set, would execute subroutines in the array controller thatinvoked PME native functions. For example a simplified array controllerprogram to do a BLAS `SAXPY` command on vectors loaded sequentiallyacross PMEs would start sequences within the PMEs that:

a. Enable PMEs with required x elements via comparison of PME id withbroadcast `incx` and `X₋₋ addr` values,

b. Compress the x values via a write to consecutive PMEs,

c. Calculate the address of PMEs with y elements from broadcast data,

d. Transmit the compressed x data to the y PMEs,

e. Do a single precision floating point operation in PMEs receiving xvalues to complete the operation.

Finally, the SAXPY example illustrates one additional aspect ofexecuting vectorized application programs. The major steps execute inthe API and could be programmed by either an optimizer or productdeveloper. Normally, the vectorized application would call rather thaninclude this level o code. These steps would be written as C or Fortrancode and will use memory mapped read or writes to control the PME arrayvia the BCI bus. Such a program operates the PME array as a series ofMIMD steps synchronized by returns to the API program. Minor steps suchas the single precision floating point routines would be developed bythe Customizer or Product Developer. These operations will be codedusing the native PME ISA and will be tuned to the machinecharacteristics. In general, this would be the domain of the ProductDeveloper since coding, test and optimization at this level requireusage of the complete product development tool set.

The APAP can have applications written in sequential Fortran. The pathis quite different. FIG. 21 outlines a Fortran compiler which can beused. In the first step, it uses a portion of the existing parallelizingcompiler to develop program dependencies. The source plus these tablesbecome an input to a process that uses a characterization of the APAPMMP and the source to enhance parallelism.

This MMP is a non-shared memory machine and as such allocates databetween the PMEs for local and global memory. The very fast datatransfer times and the high network bandwidth reduce the time affect ofdata allocation, but it still is addressed. Our approach treats part ofmemory as global and uses a S/W service function. It is also possible touse the dependency information to perform the data allocation in asecond alternative. The final step in converting the source to multiplesequential programs is performed by the Level Partitioning step. Thispartitioning step is analogous to the Fortran³ work being conducted withDARPA funding. The last process in the compilation is generation of theexecutable code at all individual functional levels. For the PME thiswill be done by programming the code generator on an existing compilersystem. The Host and API code compilers generate the code targeted tothose machines.

The PME can execute MIMD software from its own memory. In general, themultiple PMEs would not be executing totally different programs butrather would be executing the same small program in an asynchronousmanner. Three basic types of S/W can be considered although the designapproach does not limit the APAP to just these approaches:

1. Specialized emulation functions would make the PME Array emulate theset of services provide by standard user libraries like LINPACK or VPSS.In such an emulation package, the PME Array could be using its multipleset of devices to perform one of the operations required in a normalvector call. This type of emulation, when attached to a vectorprocessing unit, could utilize the vector unit for some operations whileperforming others internally.

2. The parallelism of the PME Array could be exploited by operating aset of software that provides a new set of mathematical and servicefunctions in the PMEs. This set of primitives would be the codesexploited by a customizing user to construct his application. The priorexample of performing sensor fusion on a APAP attached to a militaryplatform would use such an approach. The customizer would write routinesto perform Kalman Filters, Track Optimum Assignment and ThreatAssessment using the supplied set of function names. This applicationwould be a series of API call statements, and each call would result ininitiating the PME set to perform some basic operation like `matrixmultiply` on data stored within the PME Array.

3. In cases where no effective method, considering performanceobjectives, or application needs exists then custom S/W could bedeveloped and executed within the PME. A specific example is `Sort`.Many methods to sort data exist and the objective in all cases is totune the process and the program to the machine architecture. Themodified hypercube is well suited to a Batcher Sort; however, that sortrequires extensive calculations to determine particular elements tocompare versus very shod comparison cycles. The computer program in FIG.17 shows a simple example of a PME program 1100 to perform the BatcherSort 1000 with one element per PME. Each line of the program descriptionwould be expanded to 3 to 6 PME machine level instructions, and all PMEswould then execute the program in MIMD mode. Program synchronization ismanaged via the I/O statements. The program extends to more dataelements per PME and to very large parallel sorts in a quite straightforward manner.

CC Storage Contents

Data from the CC storage is used by the PME Array in one of two manners.When the PMEs are operating in SIMD, a series of instructions can befetched by the CC and passed to the node BCI, thus, reducing load onboth the API and CS. Alternatively, functions that are not frequentlyrequired, such as PME Fault Reconfiguration S/W, PME Diagnostics, andperhaps conversion routines can be stored in the CC memory. Suchfunctions can then be requested by operating PME MIMD programs or movedto the PMEs at the request of API program directives.

Packaging of the 8-Way Modified Hypercube

Our packaging techniques take advantage of the eight PMEs packaged in asingle chip and arranged in a N-dimensional modified hypercubeconfiguration. This chip level package or node of the array is thesmallest building block in the APAP design. These nodes are thenpackaged in an 8×8 array where the +-X and the +-Y makes rings withinthe array or cluster and the +-W, and +-Z are brought out to theneighboring clusters. A grouping of clusters make up an array. This stepsignificantly cuts down wire count for data and control for the array.The W and Z buses will connect to the adjacent clusters and form W and Zrings to provide total connectivity around the completed array ofvarious size. The massively parallel system will be comprised of thesecluster building blocks to form the massive array of PMEs. The APAP willconsist of an 8×8 array of clusters, each cluster will have its owncontroller and all the controllers will be synchronized by our ArrayDirector.

Many trade-offs of wireability and topology have been considered, yetwith these considerations we prefer the configuration which weillustrate with this connection. The concept disclosed has the advantageof keeping the X and Y dimensions within a cluster level of packaging,and distributing the W and Z bus connections to all the neighboringclusters. After implementing the techniques described, the product willbe wireable, and manufacturable while maintaining the inherentcharacteristics of the topology defined.

The concept used here is to mix, match, and modify topologies atdifferent packaging levels to obtain the desired results in terms ofwire count.

For the method to define the actual degree of modification of thehypercube, refer to the Rolfe modified hypercube patent applicationreferenced above. For the purpose of this preferred embodiment, we willdescribe two packaging levels to simplify our description. It can beexpanded.

The first is the chip design or chip package illustrated by FIG. 3 andFIG. 11. There are eight of the processing elements with theirassociated memory and communication logic encompassed into a single chipwhich is defined as a node. The internal configuration is classified asa binary hypercube or a 2-degree hypercube where every PME is connectedto two neighbors. See the PME-PME communication diagram in FIG. 9,especially 500, 510, 520, 530, 540, 550, 560, 570.

The second step is that the nodes are configured as an 8×8 array to makeup a cluster. The fully populated machine is built up of an array of 8×8clusters to provide the maximum capacity of 32768 PMEs. These 4096 nodesare connected in an 8 degree modified hypercube network where thecommunication between nodes is programmable. This ability to programdifferent routing paths adds flexibility to transmit different lengthmessages. In addition to message length differences, there are algorithmoptimizations that can be addressed with these programmability features.

The packaging concept is intended to significantly reduce the off pagewire count for each of the clusters. This concept takes a cluster whichis defined as a 8×8 array of nodes 820, each node 825 having 8processing elements for a total of 512 PMEs, then to limit the X and Yring within the cluster and, finally, to bring out the W and Z buses toall clusters. The physical picture could be envisioned as a sphereconfiguration 800, 810 of 64 smaller spheres 830. See FIG. 15 for afuture packaging picture which illustrates the full up packagingtechnique, limiting the X and Y rings 800 within the cluster andextending out the W and Z buses to all clusters 810. The physicalpicture could be envisioned as a sphere configuration of 64 smallerspheres 830.

The actual connection of a single node to the adjacent X and Y neighbors975 exists within the same cluster. The wiring savings occurs when the Zand W buses are extended to the adjacent neighboring clusters asillustrated in FIG. 16. Also illustrated in FIG. 16 is the set of thechips or nodes that can be configured as a sparsely connected4dimensional hypercube or torus 900, 905, 910, 915. Consider each of the8 external ports to be labeled as +X, +Y, +Z, +W, -X, -Y, -Z, -W 950,975. Then, using m chips, a ring can be constructed by connecting the +Xto -X ports. Again m such rings can be interconnected into a ring ofrings by interconnecting the matching +Y to -Y ports. This level ofstructure will be called a cluster. It provides for 512 PMEs and will bethe building block for several size systems. Two such connections (950,975) are shown in the diagram illustrated in FIG. 16.

Applications for Deskside MPP

The deskside MPP in a workstation can be effectively applied in severalapplication areas including:

1. Small production tasks that depend upon compute intensive processes.The US Postal Service requires a processor that can accept a fax imageof a machine printed envelope and then find and read the zip code. Theprocess is needed at all regional sort facilities and is an example of avery repetitive but still compute intensive process. We have implementedAPL language versions of a sample of the required programs. These modelsemulate the vector and array processes that will be used to do the workon the MPP. Based upon this test, we know that the task is an excellentmatch to the processing architecture.

2. Tasks in which an analyst, as a result of prior output, or expectedneeds requests sequences of data transformations. In an example takenfrom the Defense Mapping Agency, satellite images are to be transformedand smoothed pixel by pixel into some other coordinate system. In such asituation, the transformation parameters for the image vary acrosslocalities as a result of ground elevation and slope. The analyst musttherefore add fixed control points and reprocess transformations. Asimilar need occurs in the utilization of scientific simulation resultswhen users require almost real time rotation or perspective changes.

3. Program development for production versions of the MPP will useworkstation size MPPs. Consider a tuning process that requires analysisof processor versus network performance. Such a task is machine andanalyst interactive. It can require hours when the machine is idle andthe analyst is working. When performed on a supercomputer it would bevery costly. However, providing an affordable workstation MPP with thesame (but scaled) characteristics as the supercomputer MPP eliminatescosts and eases the test and debug process by eliminating the programmerinefficiencies related to accessing remote processors.

FIG. 22 is a drawing of the workstation accelerator. It uses the samesize enclosure as the RISC/6000 model 530. Two swing out gates, eachcontaining a full cluster are shown. The combined two clusters provide 5GOPS of fixed point performance and 530 MflopS of processing power andabout 100 Mbyte/s of I/O bandwidth to the array. The unit would besuitable for any of the prior applications. With quantity production andincluding a host RISC/6000, it would be price comparable with highperformance workstations, not at the price of comparable machinesemploying old technology.

Description of the AWACS Sensor Fusion

The military environment provides a series of examples showing the needfor a hardened compute intensive processor.

Communication in the targeted noisy environments implies the need fordigitally encoded communications, as is used in ICNIA systems. Theprocess of encoding the data for transmission and recovering informationafter receipt is a compute intensive process. The task can be done withspecialized signal processing modules, but for situations wherecommunication encoding represents bursts of activity, specializedmodules are mostly idle. Using the MPP permits several such tasks to beallocated to a single module and saves weight, power, volume and cost.

Sensor data fusion presents a particularly clear example of enhancing anexisting platform with the compute power gained from the addition ofMPP. On the Air Force E3 AWACS there are more than four sensors on theplatform, but there is currently no way to generate tracks resultingfrom the integration of all available data. Further, the existinggenerated tracks have quite poor quality due to samplingcharacteristics. Therefore, there is motivation to use fusion to providean effective higher sample rate.

We have studied this sensor fusion problem in detail and can propose averifiable and effective solution, but that solution would overwhelm thecompute power available in an AWACS data processor. FIG. 23 shows thetraditional track fusion process. The process is faulty because each ofthe individual processes tends to make some errors and the final mergetends to collect them instead of eliminating them. The process is alsocharacterized by high time latency in that merging does not completeuntil the slowest sensor completes. FIG. 24 presents an improvement andthe resulting compute intensive problem with the approach. Although wecannot solve a NP-Hard problem, we have developed a good method toapproximate the solution. While the details of that application arebeing described by the inventors elsewhere, as it can be employed on avariety of machines like an Intel Touchstone with 512 i860 (80860)processors, and IBM's Scientific Visualization System, it can be used asan application suitable for the MMP using the APAP design described herewith say 128,000 PMEs, substantially outperforming these other systems.Application experiments show the approximation quality is below thelevel of sensor noise and as such the answer is applicable toapplications like AWACS. FIG. 25 shows the processing loop involved inthe proposed Lagrangean Reduction n-dimensional Assignment algorithm.The problem uses very controlled repetitions of the well known2-dimensional assignment problem, the same algorithm that classicalsensor fusion processing uses.

Suppose for example that the n-dimensional algorithm was to be appliedto the seven sets of observations illustrated in FIG. 24 and further,suppose that each pass through a reduction process required fouriterations through a 2d Assignment process. Then the new 8d AssignmentProblem would require 4000 iterations of the 2d Assignment Problem. TheAWACS' workload is now about 90% of machine capacity. Fusion perhapsrequires 10% of the total effort, but even that small effort when scaledup 4000 times results in total utilization being 370 times the capacityof an AWACS. Not only does this workload overwhelm the existingprocessor, but it would be marginal in any new MIL environment suited,coarse-grained, parallel processing system currently existing oranticipated in the next few years. If the algorithm required an averageof 5 rather than 4 iterations per step, then it would overwhelm even thehypothesized systems. Conversely, the MPP solution can provide thecompute power and can do so even at the 5 iteration level.

Mechanical Packaging

As illustrated in FIG. 3, and other FIGURES, our preferred chip isconfigured in a quadflatpack form. As such it can be brickwalled intointo various 2 D and 3 D configurations in a package. One chip of eightor more processor memory elements is a first level package module, thesame as a single DRAM memory chip is to a foundry which packages thechip. However, it is in a quadflatpack form, allowing connections to oneanother in four directions. Each connection is point to point. (One chipin its first level package is a module to the foundry.) We are able toconstruct PE arrays of sufficient magnitude to hit our performance goalsdue to this feature. The reality is that you can connect these chipsacross 3, 4 or even five feet, point-to-point; i.e. multi-processor nodeto node, and still have proper control without the need of fiber optics.

This has an advantage for the drive/receive circuits that are requiredon the modules. One can achieve high performance and keep the powerdissipation down because we do not have bus systems that daisy chainfrom module to module. We broadcast from node to node, but this need notbe a high performance path. Most data operations can be conducted in anode, so data path requirements are reduced. Our broadcast path isessentially primarily used as a controller routing tool. The data streamattaches to and runs in, the ZWXY communication path system.

Our power dissipation is 2.2 watts per node module for our commercialworkstation. This allows us to use air cooled packaging. The powersystem requirements for our system are also reasonable because of thisfact. Our power system illustrated multiplies the number of modulessupported by about 2.5 watts per module, and such a five volt powersupply is very cost effective. Those concerned with the amount ofelectricity consumed would be astonished that 32 microcomputers couldoperate with less than the wattage consumed by a reading light.

Our thermal design is enhanced because of the packaging. We avoid hotspots due to high dissipating parts mixed with low dissipating ones.This reflects directly on the cost of the assemblies.

The cost of our system is very attractive compared to the approachesthat put a superscalar processor on a card. Our performance level perassembly per watt per connector per part type per dollar is excellent.

Furthermore, we do not need the same number of packaging levels that theother technology does. We do not need module/card/backplane and cable.We can skip the card level if we want to. As illustrated in ourworkstation modules, we have skipped the card level with our brickwalledapproach.

Furthermore, as we illustrated in our layout, each node housing which isbrickwalled in the workstation modules, can as illustrated in FIG. 3comprise multiple replicated dies, even within the same chip housing.While normally we would place one die within an air cooled package, itis possible to place 8 die on a substrate using a multiple chip moduleapproach. Thus, the envisioned watch with 32 or more processors, ispossible, as well as many other applications. The packaging and powerand flexibility make applications which are endless. A house could haveits controllable instruments all watched, and coordinated with a verysmall part. Those many chips that are spread around an automobile forengine watching, brake adjustment, and so on could all have a monitorwithin a housing. In addition, one the same substrate with hybridtechnology, one could mount a 386 microprocessor chip with fullprogrammable capability and memory (all in one chip) and use it as thearray controller for the substrate package.

We have shown many configurations of systems, from control systems, FIG.3, to larger and larger systems. The ability to package a chip withmultiple processor memory element of eight or more on a chip in a dip,with pinouts fitting in a standard DRAM memory module, such as in a SIMmodule make possible countless additional applications ranging fromcontrols to wall size video displays which can have a repetition rate,not a the 15 or so frames that press the existing technology today, butat 30 frames, with a processor assigned to monitor a pixel, or a nodeonly a few pixels. Our brickwall quadflatpack makes it easy to replicatethe same part time over and over again. Furthermore, the replicatedprocessor is really memory with processor interchange. Part of thememory can be assigned to a specific monitoring task, and another part(with a size programmatically defined) can be a massive global memory,addressed point-to-point, with broadcast to all capability.

Our basic workstation, our supercomputer, our controller, our AWACS, allare examples of packages that can employ our new technology. An array ofmemory, with inbuilt CPU chips and I/O, functions as a PME of massivelyparallel applications, and even more limited applications. Theflexibility of packaging and programming makes imaginations expand andour technology allows one part to be assigned to many ideas and images.

Military Avionics Applications

The cost advantage of constructing a MIL MPP is particularly wellillustrated by the AWACS. It is a 20 year old enclosure that has grownempty space as new technology memory modules have replaced the originalcore memories. FIG. 26 shows a MIL qualifiable two cluster system thatwould fit directly into the rack's empty space and would use theexisting memory bus system for interconnection.

Although the AWACS example is very advantageous due to the existence ofempty space, in other systems it is possible to create space. Replacingexisting memory with a small MPP or gateway to an an isolated MPP isnormally quite viable. In such cases, a quarter cluster and a adaptermodule would result in a 8 Megabyte memory plus 640 MIPs and use perhapstwo slots.

Supercomputer Application

A 64 cluster MPP is a 13.6 Gflop supercomputer. It can be configured ina system described in FIG. 27. The system we describe allows node chipsto be brick walled on cluster cards as illustrated in FIG. 27 to buildup systems with some significant cost and size advantages. There is noneed to include extra chips such as a network switch in such a systembecause it would increase costs.

Our interconnection system with "brickwalled" chips allows systems to bebuilt like massive DRAM memory is packaged and will have a defined busadapter conforming to the rigid bus specifications, for instance amicrochannel bus adaptor. Each system will have a smaller power supplysystem and cooling design than other systems based upon many modernmicroprocessors.

Unlike most supercomputers our current preferred APAP with floatingpoint emulation is much faster in integer arithmetic (164 GIPS) than itis when doing floating point arithmetic. As such, the processor would bemost effective when used in applications that are very character orinteger intensive. We have considered three program challenges which inaddition to the other applications discussed herein are needful ofsolution. The applications which may be more important than some of the"grand challenges" to day to day life include:

1. 3090 Vector Processors contain a very high performance floating pointarithmetic unit. That unit, as do most vectorized floating point units,requires pipeline operations on dense vectors. Applications that makeextensive use of non-regular sparse matrices (i.e. matrices described bybit maps rather than diagonals) waste the performance capability of thefloating point unit. The MPP solves this problem by providing thestorage for the data and using its compute power and network bandwidth,not to do the calculation but rather to construct dense vectors, and todecompress dense results. The Vector Processing Unit is kept busy by acontinual flow of operations on dense vectors being supplied to it bythe MPP. By sizing the MPP so that it can effectively compress anddecompress at the same rate the Vector Facility processes, one couldkeep both units fully busy.

2. Another host attached system we considered is a solution to the FBIfingerprint matching problem. Here, a machine with more than 64 clusterswas considered. The problem was to match about 6000 fingerprints perhour against the entire database of fingerprint history. Using massiveDASD and the full bandwidth of the MPP to host attachment, one can rollthe complete data base across the incoming prints in about 20 minutes.Operating about 75% of the MPP in a SIMD mode coarse matching operation,balances processing to required throughput rate. We estimate that 15% ofthe machine in A-SIMD processing mode would then complete the matchingby doing the detailed verification of unknown print versus file printfor cases passing the coarse filter operation. The remaining portions ofthe machine were in MIMD mode and allocated to reserve capacity, workqueue management and output formatting.

3. Application of the MPP to database operations has been considered.Although the work is very preliminary, it does seem to be a good match.Two aspects of the MPP support this premise:

a. The connection between a cluster Controller and the ApplicationProcessor Interface is a MicroChannel. As such, it could be populatedwith DASD dedicated to the cluster and accessed directly from thecluster. A 64 cluster system with six 640 Mbyte hard drives attached percluster would provide 246 Gbyte storage. Further, that entire databasecould be searched sequentially in 10 to 20 seconds.

b. Databases are generally not searched sequentially. Instead they usemany levels of pointers. Indexing of databases can be done within thecluster. Each bank of DASD would be supported by 2.5 GIPS of processingpower and 32 Mbyte of storage. That is sufficient for both searching andstoring the indices. Since indices are now frequently stored within theDASD, significant performance gains would occur. Using such an approachand dispersing DASD on SCSI interfaces attached to the clusterMicroChannel permits effectively unlimited size data bases.

FIG. 27 is an illustration of the APAP when used to build the systeminto a supercomputer scaled MPP. The approach reveals to replicatingunits, but here it is enclosures containing 16 clusters that arereplicated. The particular advantage of this replication approach isthat the system can be scaled to suit the user's needs.

System Architecture

An advantage of the system architecture which is employed in the currentpreferred embodiment is the ISA system which will be understood by manywho will form a pool for programming the APAP. The PME ISA consists ofthe following Data and Instruction Formats. illustrated in the Tables.

Data Formats

The basic (operand) size is the 16 bit word. In PME storage, operandsare located on integral word boundaries. In addition to the word operandsize, other operand sizes are available in multiples of 16 bits tosupport additional functions.

Within any of the operand lengths, the bit positions of the operand areconsecutively numbered from left to right starting with the number 0.Reference to high-order or most-significant bits always refer to theleft-most bit positions. Reference to the low-order or least-significantbits always refer to the right-most bit positions.

Instruction Formats

The length of an instruction format may either be 16 bits or 32 bits. InPME storage, instructions must be located on a 16 bit boundary.

The following general instruction formats are used. Normally, the firstfour bits of an instruction define the operation code and are referredto as the OP bits. In some cases, additional bits are required to extendthe definition of the operation or to define unique conditions whichapply to the instruction. These bits are referred to as OPX bits.

    ______________________________________                                        Format Code       Operation                                                   ______________________________________                                        RR                Register to Register                                        DA                Direct Address                                              RD                Register Storage                                            RI                Register Immediate                                          SS                Storage to Storage                                          SPC               Special                                                     ______________________________________                                    

All formats have one field in common. This field and its interpretationis:

Bits 0-3 Operation Code--This field, sometimes in conjunction with anoperation code extension field, defines the operation to be performed.

Detailed figures of the individual formats along with interpretations oftheir fields are provided in the following subsections. For someinstructions, two formats may be combined to form variations on theinstruction. These primarily involve the addressing mode for theinstruction. As an example a storage to storage instruction may have aform which involves direct addressing or register addressing.

RR Format

The Register-Register (RR) format provides two general registeraddresses and is 16 bits in length as shown. ##STR1##

In addition to an Operation Code field, the RR format contains:

Bits 4-7 Register Address 1--The RA field is used to specify which ofthe 16 general registers is to be used as an operand and/or destination.

Bits 8-11 Zeros--Bit 8 being a zero defines the format to be a RR or DAformat and bits 9-11 equal to zero define the operation to be a registerto register operation (a special case of the Direct Address format).

Bits 12-15 Register Address 2--The RB field is used to specify which ofthe 16 general registers is to be used as an operand.

DA Format

The Direct Address (DA) format provides one general register address andone direct storage address as shown. ##STR2##

In addition to an Operation Code field, the DA format contains:

Bits 4-7 Register Address 1--The RA field is used to specify which ofthe 16 general registers is to be used as an operand and/or destination.

Bit 8 Zero--This bit being zero defines the operation to be a directaddress operation or a register to register operation.

Bits 9-15 Direct Storage Address--The Direct Storage Address field isused as an address into the level unique storage block or the commonstorage block. Bits 9-11 of the direct address field must be non-zero todefine the direct address form.

RS Format

The Register Storage (RS) format provides one general register addressesand an indirect storage address. ##STR3##

In addition to an Operation Code field, the RS format contains:

Bits 4-7 Register Address 1--The RA field is used to specify which ofthe 16 general registers is to be used as an operand and/or destination.

Bit 8 One--This bit being one defines the operation to be a registerstorage operation.

Bits 9-11 Register Data--These bits are considered a signed value whichis used to modify the contents of register specified by the RB field.

Bits 12-15 Register Address 2--The RB field is used to specify which ofthe 16 general registers is to be used as an storage address for anoperand.

RI Format

The Register-Immediate (RI) format provides one general register addressand 16 bits of immediate data. The RI format is 32 bits of length asshown: ##STR4##

In addition to an Operation Code field, the RI format contains:

Bits 4-7 Register Address 1--The RA field is used to specify which ofthe 16 general registers is to be used as an operand and/or destination.

Bit 8 One--This bit being one defines the operation to be a registerstorage operation.

Bits 9-11 Register Data--These bits are considered a signed value whichis used to modify the contents of the program counter. Normally, thisfield would have a value of one for the register immediate format.

Bits 12-15 Zeroes--The field being zero is used to specify that theupdated program counter, which points to the immediate data field, is tobe used as an storage address for an operand.

Bits 16-31 Immediate Data--This field serves as a 16 bit immediate dataoperand for Register Immediate instructions.

SS Format

The Storage to Storage (SS) format provides two storage addresses, oneexplicit; and the second implicit. The implied storage address iscontained in General Register 1. Register 1 is modified during executionof the instruction. There are two forms of a SS instruction, a directaddress form and a storage address form. ##STR5##

In addition to an Operation Code field, the SS format contains:

Bits 4-7 Operation Extension Code--The OPX field, together with theOperation Code, defines the operation to be performed. Bits 4-5 definethe operation type such as ADD or SUBTRACT. Bits 6-7 control the carry,overflow, and how the condition code will be set. Bit 6=0 ignoresoverflow, bit 6=1 allows overflow. Bit 7=0 ignore the carry stat duringthe operation; bit 7=1 includes the carry stat during the operation.

Bit 8 Zero--Defines the form to be a direct address form. One--Definesthe form to be a storage address form.

Bits 9-15 Direct Address (Direct Address Form)--The Direct StorageAddress field is used as an address into the level unique storage blockor the common storage block. Bits 9-11 of the direct address field mustbe non-zero to define the direct address form.

Bits 9-11 Register Delta (Storage Address Form)--These bits areconsidered a signed value which is used to modify the contents ofregister specified by the RB field.

Bits 12-15 Register Address 2 (Storage Address Form)--The RB field isused to specify which of the 16 general registers is to be used as astorage address for an operand.

SPC Format 1

The Special (SPC1) format provides one general register storage operandaddress. ##STR6##

In addition to an Operation Code field, the SPC1 format contains:

Bits 4-7 OP Extension--The OPX field is used to extend the operationcode.

Bit 8 Zero or One--This bit being zero defines the operation to be aregister operation. This bit being one defines the operation to be aregister storage operation.

Bits 9-11 Operation Length--These bits are considered an unsigned valuewhich is used to specify the length of the operand in 16 bit words. Avalue of zero corresponds to a length of one, and a value of B`111`corresponds to a length of eight.

Bits 12-15 Register Address 2--The RB field is used to specify which ofthe 16 general registers is to be used as a storage address for theoperand.

SPC Format 2

The Special (SPC2) format provides one general register storage operandaddress. ##STR7##

In addition to an Operation Code field, the SPC2 format contains:

Bits 4-7 Register Address 1--The RA field is used to specify which ofthe 16 general registers is to be used as an operand and/or destination.

Bits 8-11 OP Extension--The OPX field is used to extend the operationcode.

Bits 12-15 Register Address 2--The RB field is used to specify which ofthe 16 general registers is to be used as a storage address for theoperand.

THE INSTRUCTION LIST OF THE ISA INCLUDES THE FOLLOWING:

                  TABLE 1                                                         ______________________________________                                        Fixed-Point Arithmetic Instructions                                                                  MNE-                                                   NAME                   MONIC    TYPME                                         ______________________________________                                        ADD DIRECT             ada      DA                                            ADD FROM STORAGE       a        RS                                            (WITH DELTA)           awd      RS                                            ADD IMMEDIATE          ai       RI                                            (WITH DELTA)           aiwd     RI                                            ADD REGISTER           ar       RR                                            COMPARE DIRECT ADDRESS cda      DA                                            COMPARE IMMEDIATE      ci       RI                                            (WITH DELTA)           ciwd     RI                                            COMPARE FROM STORAGE   c        RS                                            (WITH DELTA)           cwd      RS                                            COMPARE REGISTER       cr       RR                                            COPY                   cpy      RS                                            (WITH DELTA)           cpywd    RS                                            COPY WITH BOTH IMMEDIATE                                                                             cpybi    RI                                            (WITH DELTA)           cpybiwd  RI                                            COPY IMMEDIATE         cpyi     RI                                            (WITH DELTA)           cpyiwd   RI                                            COPY DIRECT            cpyda    DA                                            COPY DIRECT IMMEDIATE  cpydai   DA                                            INCREMENT              inc      RS                                            (WITH DELTA)           incwd    RS                                            LOAD DIRECT            lda      DA                                            LOAD FROM STORAGE      l        RS                                            (WITH DELTA)           lwd      RS                                            LOAD IMMEDIATE         li       RI                                            (WITH DELTA)           liwd     RI                                            LOAD REGISTER          lr       RR                                            MULTIPLY SIGNED        mpy      SPC                                           MULTIPLY SIGNED EXTENDED                                                                             mpyx     SPC                                           MULTIPLY SIGNED EXTENDED                                                                             mpyxi    SPC                                           IMMEDIATE                                                                     MULTIPLY SIGNED IMMEDIATE                                                                            mpyi     SPC                                           MULTIPLY UNSIGNED      mpyu     SPC                                           MULTIPLY UNSIGNED EXTENDED                                                                           mpyux    SPC                                           MULTIPLY UNSIGNED EXTENDED                                                                           mpyuxi   SPC                                           IMMEDIATE                                                                     MULTIPLY UNSIGNED IMMEDIATE                                                                          mpyui    SPC                                           STORE DIRECT           stda     DA                                            STORE                  st       RS                                            (WITH DELTA)           stwd     RS                                            STORE IMMEDIATE        sti      RI                                            (WITH DELTA)           stiwd    RI                                            SUBTRACT DIRECT        sda      DA                                            SUBTRACT FROM STORAGE  s        RS                                            (WITH DELTA)           swd      RS                                            SUBTRACT IMMEDIATE     si       RI                                            (WITH DELTA)           siwd     RI                                            SUBTRACT REGISTER      sr       RR                                            SWAP AND EXCLUSIVE OR WITH                                                                           swapx    RR                                            STORAGE                                                                       ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Storage to Storage Instructions                                                                      MNE-                                                   NAME                   MONIC    TYPME                                         ______________________________________                                        ADD STORAGE TO STORAGE sa       SS                                            (WITH DELTA)           sawd     SS                                            ADD STORAGE TO STORAGE sada     SS                                            DIRECT                                                                        ADD STORAGE TO STORAGE FINAL                                                                         saf      SS                                            (WITH DELTA)           safwd    SS                                            ADD STORAGE TO STORAGE FINAL                                                                         safda    SS                                            DIRECT                                                                        ADD STORAGE TO STORAGE sai      SS                                            INTERMEDIATE                                                                  (WITH DELTA)           saiwd    SS                                            ADD STORAGE TO STORAGE                                                        INTERMEDIATE                                                                  DIRECT                 saida    SS                                            ADD STORAGE TO STORAGE sal      SS                                            LOGICAL                                                                       (WITH DELTA)           salwd    SS                                            ADD STORAGE TO STORAGE salda    SS                                            LOGICAL DIRECT                                                                COMPARE STORAGE TO STORAGE                                                                           sc       SS                                            (WITH DELTA)           scwd     SS                                            COMPARE STORAGE TO STORAGE                                                                           scda     SS                                            DIRECT                                                                        COMPARE STORAGE TO STORAGE                                                                           scf      SS                                            FINAL                                                                         (WITH DELTA)           scfwd    SS                                            COMPARE STORAGE TO STORAGE                                                                           scfda    SS                                            FINAL DIRECT                                                                  COMPARE STORAGE TO STORAGE                                                                           sci      SS                                            INTERMEDIATE                                                                  (WITH DELTA)           sciwd    SS                                            COMPARE STORAGE TO STORAGE                                                    INTERMEDIATE                                                                  DIRECT                 scida    SS                                            COMPARE STORAGE TO STORAGE                                                                           scl      SS                                            LOGICAL                                                                       (WITH DELTA)           sclwd    SS                                            COMPARE STORAGE TO STORAGE                                                    LOGICAL                                                                       DIRECT                 sclda    SS                                            MOVE STORAGE TO STORAGE                                                                              smov     SS                                            (WITH DELTA)           smovwd   SS                                            MOVE STORAGE TO STORAGE                                                                              smovda   SS                                            DIRECT                                                                        SUBTRACT STORAGE TO STORAGE                                                                          ss       SS                                            (WITH DELTA)           sswd     SS                                            SUBTRACT STORAGE TO STORAGE                                                                          sada     SS                                            DIRECT                                                                        SUBTRACT STORAGE TO STORAGE                                                                          ssf      SS                                            FINAL                                                                         (WITH DELTA)           ssfwd    SS                                            SUBTRACT STORAGE TO STORAGE                                                                          ssfda    SS                                            FINAL DIRECT                                                                  SUBTRACT STORAGE TO STORAGE                                                                          ssi      SS                                            INTERMEDIATE                                                                  (WITH DELTA)           ssiwd    SS                                            SUBTRACT STORAGE TO STORAGE                                                   INTERMEDIATE                                                                  DIRECT                 saida    SS                                            SUBTRACT STORAGE TO STORAGE                                                                          ssl      SS                                            LOGICAL                                                                       (WITH DELTA)           sslwd    SS                                            SUBTRACT STORAGE TO STORAGE                                                   LOGICAL                                                                       DIRECT                 sslda    SS                                            ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Logical Instructions                                                                              MNE-                                                      NAME                MONIC      TYPME                                          ______________________________________                                        AND DIRECT ADDRESS  nda        DA                                             AND FROM STORAGE    n          RS                                             (WITH DELTA)        nwd        RS                                             AND IMMEDIATE       ni         RI                                             (WITH DELTA)        niwd       RI                                             AND REGISTER        nr         RR                                             OR DIRECT ADDRESS   oda        DA                                             OR FROM STORAGE     o          RS                                             (WITH DELTA)        owd        RS                                             OR IMMEDIATE        oi         RI                                             (WITH DELTA)        oiwd       RI                                             OR REGISTER         or         RR                                             XOR DIRECT ADDRESS  xda        DA                                             XOR FROM STORAGE    x          RS                                             (WITH DELTA)        xwd        RS                                             XOR IMMEDIATE       xi         RI                                             (WITH DELTA)        xiwd       RI                                             XOR REGISTER        xr         RR                                             ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Shift Instructions                                                                                   MNE-                                                   NAME                   MONIC    TYPME                                         ______________________________________                                        SCALE BINARY           scale    SPC                                           SCALE BINARY IMMEDIATE scalei   SPC                                           SCALE BINARY REGISTER  scaler   SPC                                           SCALE HEXADECIMAL      scaleh   SPC                                           SCALE HEXADECIMAL IMMEDIATE                                                                          scalehi  SPC                                           SCALE HEXADECIMAL REGISTER                                                                           scalehr  SPC                                           SHIFT LEFT ARITHMETIC BINARY                                                                         sla      SPC                                           SHIFT LEFT ARITHMETIC BINARY                                                                         slai     SPC                                           IMMEDIATE                                                                     SHIFT LEFT ARITHMETIC BINARY                                                                         slar     SPC                                           REGISTER                                                                      SHIFT LEFT ARITHMETIC  slah     SPC                                           HEXADECIMAL                                                                   SHIFT LEFT ARITHMETIC  slahi    SPC                                           HEXADECIMAL IMMEDIATE                                                         SHIFT LEFT ARITHMETIC  slahr    SPC                                           HEXADECIMAL REGISTER                                                          SHIFT LEFT LOGICAL BINARY                                                                            sll      SPC                                           SHIFT LEFT LOGICAL BINARY                                                                            slli     SPC                                           IMMEDIATE                                                                     SHIFT LEFT LOGICAL BINARY                                                                            sllr     SPC                                           REGISTER                                                                      SHIFT LEFT LOGICAL     sllh     SPC                                           HEXADECIMAL                                                                   SHIFT LEFT LOGICAL     sllhi    SPC                                           HEXADECIMAL IMMEDIATE                                                         SHIFT LEFT LOGICAL     sllhr    SPC                                           HEXADECIMAL REGISTER                                                          SHIFT RIGHT ARITHMETIC BINARY                                                                        sra      SPC                                           SHIFT RIGHT ARITHMETIC BINARY                                                                        srai     SPC                                           IMMEDIATE                                                                     SHIFT RIGHT ARITHMETIC BINARY                                                                        srar     SPC                                           REGISTER                                                                      SHIFT RIGHT ARITHMETIC srah     SPC                                           HEXADECIMAL                                                                   SHIFT RIGHT ARITHMETIC srahi    SPC                                           HEXADECIMAL IMMEDIATE                                                         SHIFT RIGHT ARITHMETIC srahr    SPC                                           HEXADECIMAL REGISTER                                                          SHIFT RIGHT LOGICAL BINARY                                                                           srl      SPC                                           SHIFT RIGHT LOGICAL BINARY                                                                           srli     SPC                                           IMMEDIATE                                                                     SHIFT RIGHT LOGICAL BINARY                                                                           srlr     SPC                                           REGISTER                                                                      SHIFT RIGHT LOGICAL    srlh     SPC                                           HEXADECIMAL                                                                   SHIFT RIGHT LOGICAL    srlhi    SPC                                           HEXADECIMAL IMMEDIATE                                                         SHIFT RIGHT LOGICAL    srlhr    SPC                                           HEXADECIMAL REGISTER                                                          ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        Branch Instructions                                                                                  MNE-                                                   NAME                   MONIC    TYPME                                         ______________________________________                                        BRANCH                 b        RS                                            (WITH DELTA)           bwd      RS                                            BRANCH DIRECT          bda      DA                                            BRANCH IMMEDIATE       bi       RI                                            (WITH DELTA)           biwd     RI                                            BRANCH REGISTER        br       RS                                            BRANCH AND LINK        bal      RS                                            BRANCH AND LINK DIRECT balda    DA                                            BRANCH AND LINK IMMEDIATE                                                                            bali     RI                                            (WITH DELTA)           baliwd   RI                                            BRANCH AND LINK REGISTER                                                                             balr     RS                                            BRANCH BACKWARD        bb       RS                                            (WITH DELTA)           bbwd     RS                                            BRANCH BACKWARD DIRECT bbda     DA                                            BRANCH BACKWARD IMMEDIATE                                                                            bbi      RI                                            (WITH DELTA)           bbiwd    RI                                            BRANCH BACKWARD REGISTER                                                                             bbr      RS                                            BRANCH FORWARD         bf       RS                                            (WITH DELTA)           bfwd     RS                                            BRANCH FORWARD DIRECT  bfda     DA                                            BRANCH FORWARD IMMEDIATE                                                                             bfi      RI                                            (WITH DELTA)           bfiwd    RI                                            BRANCH FORWARD REGISTER                                                                              bfr      RS                                            BRANCH ON CONDITION    bc       RS                                            (WITH DELTA)           bcwd     RS                                            BRANCH ON CONDITION DIRECT                                                                           bcda     RS                                            BRANCH ON CONDITION    bci      RI                                            IMMEDIATE                                                                     (WITH DELTA)           bciwd    RI                                            BRANCH ON CONDITION REGISTER                                                                         bcr      RS                                            BRANCH RELATIVE        brel     RI                                            (WITH DELTA)           brelwd   RS                                            NULL OPMERATION        noop     RR                                            ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Status Switching Instructions                                                                 MNE-                                                          NAME            MONIC    TYPME                                                ______________________________________                                        RETURN          ret      SPC                                                  ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Input/Output Instructions                                                                         MNE-                                                      NAME                MONIC      TYPME                                          ______________________________________                                        IN                  IN         SPC                                            OUT                 OUT        SPC                                            INTERNAL DIOR/DIOW  INTR       SPC                                            ______________________________________                                    

SOME SUMMARY FEATURES The APAP Machine in Perspective

We have described in accordance with our invention could be thought ofin its more detailed aspects to be positioned in the technologysomewhere between the CM-1 and N-cube. Like our APAP, the CM-1 uses apoint design for the processing element and combines processing elementswith memory on the basic chip. The CM-1, however uses a 1 bit wideserial processor, while the APAP series will use a 16 bit wideprocessor. The CM series of machines started with 4K bits of memory perprocessor and has grown to 8 or 16K bits versus the 32K by 16 bits wehave provided for the first APAP chip. The CM-1 and its follow-ons arestrictly SIMD machines while the CM-5 is a hybrid. Instead of this, ourAPAP will effectively use MIMD operating modes in conjunction with SIMDmodes when useful. While our parallel 16 bit wide PMEs might be viewedas a step toward the N-cube, this step is not warranted. The APAP doesnot separate memory and routing from the processing element as does theN-cube kind of machine. Also, the APAP provides for up to 32K 16 bitPMEs while the N-cube only provides for 4K 32 bit processors.

Even with the superficial similarities presented above, the APAP conceptcompletely differs from the CM and N-cube series by:

1. The modified hypercube incorporated in our APAP is a new inventionproviding a significant packaging and addressing advantage when comparedwith hypercube topologies. For instance, consider that the 32K PME APAPin its first preferred embodiment has a network diameter of 19 logicalsteps and, with transparency, this can be reduced to an effective 16logical steps. Further, by comparison, if a pure hypercube were used,and if all PMEs were sending data through an 8 step path, then onaverage 2 of every 8 PMEs would be active while the remainder would bedelayed due to blockage.

Alternatively, consider the 64K hypercube that would be needed if CM-1was a pure hypercube. In that case, each PME would require ports to 16other PMEs, and data could be routed between the two farthest separatedPMEs in 15 logical steps. If all PMEs tried to transfer an averagedistance of 7 steps, the 2 of every 7 would be active. However, CM-1does not utilize a 16d hypercube. It interconnects the 16 nodes on achip with a NEWS network; then it provides one router function withinthe chip. The 4096 routers are connected into a 12d hypercube With nocollisions the hybrid still has a logical diameter of 15, but since 16PMEs could be contending for the link its effective diameter is muchgreater. That is, with 8 step moves only 2 of 16 PMEs could be active,which means that 8 complete cycles rather than 4 cycles are needed tocomplete all data moves.

The N-cube actually utilizes a pure hypercube, but currently onlyprovides for a 4096 PMEs and thus, utilizes a 12d (13d for 8192 PMEs)hypercube. For the N-cube to grow to 16K processors, at which point itwould have the same processing data width as the APAP, it would have toadd four times as much hardware and would have to increase theconnection ports to each PME router by 25%. Although no hard data existsto support this conclusion, it would appear that the N-cube architectureruns out of connector pins prior to reaching a 16K PME machine.

2. The completely integrated and distributed nature of major taskswithin the APAP machine is a decided advantage. As was noted for the CMand N-cube series of machines, each had to have separate units formessage routing as well as separate units for floating pointcoprocessors. The APAP system combines the integer, floating pointprocessing, message routing and I/O control into the single point designPME. That design is then replicated 8 times on a chip, and the chip isthen replicated 4K times to produce the array. This provides severaladvantages:

a. Using one chip means maximum size production runs and minimal systemfactor costs.

b. Regular architecture produces the most effective programming systems.

c. Almost all chip pins can be dedicated to the generic problem ofinterprocessor communication, maximizing the inter-chip I/O bandwidthwhich tends to be a important limiting factor in MPP designs.

3. The APAP has the unique design ability to take advantage of chiptechnology gains and capital investment in custom chip designs.

Consider the question of floating point performance. It is anticipatedthat APAP PME performance on DAXPY will be about 125 cycles per flop. Incontrast, the '387 Coprocessor would be about 14 cycles while the WeitecCoprocessor in the CM-1 would be about 6 cycles. However, in the CM casethere is only one floating point unit for every 16 PMEs while in theN-cube case there is probably one '387 type chip associated with each ofthe '386 processors. Our APAP has 16 times as many PMEs and thereforecan almost completely make up for the single unit performance delta.

More significantly, the 8 APAP PMEs within a chip are constructed from50K gates currently available in the technology. As memory macros shrinkand the number of gates available to the logic increases. Spending thatincrease on enhanced floating point normalization should permit APAPfloating point performance to far exceed the other units. Alternatively,effort could be spent to generate a PME or PME subsection design usingcustom design approaches, enhancing total performance while in no wayaffecting any S/W developed for the machine.

We believe our design for our APAP has characteristics poised to takeadvantage of the future process technology growth. In contrast, thenearest similar machines CM-x and N-cube which employ a system like thatdescribed in FIG. 1 seem well poised to take advantage of yesterday'stechnology which we feel is dead ended.

An advantage of the APAP concept is the ability to use DASD associatedwith groups of PMEs. This APAP capability, as well as the ability toconnect displays and auxiliary storage, is a by-product of picking MCbus structures as the interface to the external I/O ports of the PMEArray. Thus, APAP systems will be configurable and can include cardmounted hard drives selected from one of the set of units that arecompatible with PS/2 or RISC/6000 units. Further, that capability shouldbe available without designing any additional part number modulesalthough it does require utilizing more replications of the backpaneland base enclosure than does the APAP.

This brief perspective is not intended to be limiting, but rather isintended to cause those skilled in the art to review the foregoingdescription and examine how the many inventions we have described whichmay be used to move the art of massively parallel systems ahead to atime when programming is no longer a significant problem and the costsof such systems are much lower. Our kind of system can be madeavailable, not only to the few, but to many as it could be made at acost within the reach of commercial department level procurements.

While we have described our preferred embodiments of our invention, itwill be understood that those skilled in the art, both now and in thefuture, upon the understanding of these discussions will make variousimprovements and enhancements thereto which fall within the scope of theclaims which follow. These claims should be construed to maintain theproper protection for the invention first disclosed.

What is claimed is:
 1. A computer system, comprising:a plurality ofprocessor-memory elements (PME's), each processor-memory element (PME)containing a processor, a memory, and a multi-bit parallel data paththerebetween; a plurality of nodes interconnected as a multi-dimensionalnetwork cluster, each node containing a plurality of processor-memoryelements (PME's); and a cluster controller for said plurality of nodes;wherein each processor-memory element (PME) of a node has a plurality ofcommunication paths to processor-memory elements (PME's) within the nodeand at least one communication path to a processor-memory element (PME)external to the node.
 2. A computer system according to claim 1 whereinsaid array director has overall control of a cluster providing clustercontrol for an array of nodes.
 3. A computer system according to claim 1wherein said computer system is provided with a plurality of clustersand said array director has overall control of the clusters providingcluster control for an array of nodes, and cluster synchronization foran array of clusters.
 4. A computer system according to claim 1 whereinsaid computer system is provided with a plurality of clusters and saidarray director has overall control of the clusters providing clustercontrol for an array of nodes, and cluster synchronization for an arrayof clusters, and an I/O zipper connected between nodes of saidprocessing array for data transfer with said processing array along theedges of selected clusters.
 5. A computer system according to claim 1wherein said computer system is provided with a plurality of clustersand said array director has overall control of the clusters providingcluster control for an 8×8 array of clusters, and an I/O zipperconnected between nodes of said processing array for data transfer withsaid processing array along the edges of selected clusters.
 6. Acomputer system according to claim 1 wherein a node includes multipleprocessor-memory elements (PME's) of an parallel array processor,incorporating a plurality of identical processor-memory elements (PME's)in an array cluster.
 7. A computer system according to claim 1 wherein anode includes multiple processor-memory elements (PME's) of an parallelarray processor incorporating array clusters in a parallel arraycomputer system having said array director.
 8. A computer systemaccording to claim 1 wherein a node includes multiple processor-memoryelements (PME's) of an parallel array processor incorporating arrayclusters in a parallel array computer system having said array directorfor controlling clusters, and said application processor interfaceproviding a test/debug unit for design, debug, and monitoring functions.9. A computer system according to claim 1 wherein a node forms part of acluster, each node having a set of multiple processor-memory elements(PME's), and wherein a complete set of processor memory-elements (PME's)may be divided into distinct subsets under control of said arraydirector to interleave between subsets.
 10. A computer system accordingto claim 1 wherein a node forms part of a cluster, each node having aset of multiple processor-memory elements (PME's), and wherein acomplete set of processor-memory elements (PME's) may be divided intodistinct subsets under control of said array director to interleavebetween subsets, the sequence of the interleave process and the amountof control exercised over each subset being program controlled by saidarray director.
 11. A computer system according to claim 1 wherein anode forms part of a cluster, each node having a set of multipleprocessor-memory elements (PME's), and wherein a complete set ofprocessor-memory elements (PME's) may be divided into distinct subsetsunder control of said array director to interleave between subsets tooperate distinct subsets of the array in one mode while other setsoperate in tightly synchronized SIMD mode under array director control.12. A computer system according to claim 1 wherein a node broadcast andcontrol interface provides a parallel input interface and also providestwo serial port interfaces for each processor-memory element (PME) tooutput a limited amount of status information for signaling said arraydirector when the processor-memory element (PME) has data that needs tobe read.
 13. A computer system according to claim 1 wherein a nodebroadcast and control interface provides a parallel input interface andalso provides two serial port interfaces for each processor-memoryelement (PME) to output activity status information such that test andmonitor displays illustrates the status of the entire system of which anode forms a part.
 14. A computer system according to claim 1 wherein anode broadcast and control interface provides a parallel input interfaceand also provides two serial port interfaces providing a serial port foran array director to input control data so as to direct the port toparticular processor memory elements (PME's) and node internal registersand access points.
 15. A computer system according to claim 1 wherein anode broadcast and control interface is coupled to a node controllercoupled though a set of nodes with a serial scan loop for acquiringinformation on individual nodes or processor-memory elements (PME's)within a node.
 16. A computer system according to claim 1 wherein saidarray director includes I/O means for breaking a connection to a node.